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What Is Kaizen? Meaning, Principles and How It Works on the Shop Floor

Kaizen is Japanese for improvement. What it means in practice, where it came from, daily kaizen versus kaizen events, how it relates to Lean, and how to start.

13 min readUpdated Alexander Wennerberg

Kaizen (改善) is the Japanese word for improvement. In management it means continuous improvement: small, practical changes to how work is done, suggested and made by the people who do that work, every day, against an agreed standard. The term reached Western managers through Masaaki Imai’s 1986 book Kaizen: The Key to Japan’s Competitive Success, and Toyota, where much of the practice took shape, says all of its employees carry out daily, incremental kaizen. Below: the meaning, the origins, the principles, daily kaizen versus kaizen events, how kaizen compares with Lean and Six Sigma, and how to start.

Kaizen is one way of doing continuous improvement, not the whole of it. For the wider picture, including PDCA in depth and what ISO 9001 asks for, see what continuous improvement is.

What does kaizen mean?

Kaizen is written with two characters. 改 (kai) means change, reform or mend. 善 (zen) means good or virtuous. Together they make an ordinary Japanese noun that dictionaries gloss as betterment or improvement.

Dictionaries such as JMdict list two meanings: the everyday one, improvement, and a separate business one, the philosophy of continuous improvement. The ideas of “continuous” and “everyone” belong to the second, the way Japanese industry and later Western management used the word. Imai defined kaizen in the workplace as ongoing improvement that involves everyone, managers and workers alike.

On a production floor that looks like this: an operator points out that a tool is fetched from the far end of the line at every changeover, the tool gets a holder at the station this week, and the work instruction changes to match. No business case: a small change, owned by the people doing the job, that becomes the new standard.

Where does kaizen come from?

No single person invented kaizen. The practice grew out of several post-war strands in Japanese industry, and the word reached Western management decades later.

  • Training Within Industry. After the Second World War, the US Training Within Industry (TWI) programmes came to Japan under the Occupation. One, Job Methods, taught supervisors a four-step way to improve the jobs they ran. Jim Huntzinger’s history of TWI, published by the Lean Enterprise Institute (LEI), argues that Job Methods was the original form of kaizen.
  • PDCA. In 1950 W. Edwards Deming taught an improvement cycle to Japanese engineers, and in 1951 the Japanese Union of Scientists and Engineers (JUSE) reworked it into Plan-Do-Check-Act. Deming shaped the cycle kaizen runs on, not kaizen itself.
  • Toyota’s suggestion system. In May 1951 Toyota launched its Creative Idea Suggestion System, modelled on Ford’s, to gather ideas from a wide range of employees. This is where kaizen and employee ideas meet.
  • The Toyota Production System. Toyota credits Eiji Toyoda and Taiichi Ohno with building it on two pillars: jidoka (stopping when something is wrong, so a defect is not passed on) and just-in-time (making only what is needed, when it is needed, in the amount needed). Toyota puts kaizen at the foundation of jidoka.
  • Masaaki Imai. Imai, born in Tokyo in 1930, worked with Ohno in the 1980s to spread the Toyota Production System. His consultancy, the Kaizen Institute, was incorporated in Switzerland in 1985, and his book Kaizen: The Key to Japan’s Competitive Success (McGraw-Hill, 1986) put the word into Western management vocabulary. Gemba Kaizen followed in 1997. Imai died in 2023.

You will often read that Ohno coined the term. We could not find a source that supports it. Ohno built the system in which kaizen became a daily routine; the word itself is an ordinary Japanese noun.

What are the principles of kaizen?

The Kaizen Institute sums up kaizen in five principles:

Principle What it means in practice
Know your customer Every improvement makes things better for whoever receives the work, the next station included
Let it flow Remove waiting, searching and rework so work moves without stopping
Go to gemba Look at the real place where the work happens before deciding anything
Empower people The people doing the job suggest and make the changes, with time and authority to do so
Be transparent Problems, results and the status of every improvement idea are visible to everyone

Three more come from Toyota and the LEI.

No kaizen without a standard. The LEI quotes Ohno: “There can be no kaizen without a standard.” A standard is the current best way to do a job, written down. You improve against it, and once a change works, you update it so the gain does not disappear. The operation also has to be stable first (machines working, people present, material available), or teams improve on top of chaos and the gains vanish.

Respect for people. The Toyota Way 2001 set out two main principles, continuous improvement and respect for people, with kaizen as one of five key concepts beneath them. The pairing is the point: nobody suggests improving their own job away.

PDCA as the working cycle. Each improvement runs through Plan, Do, Check, Act, and the LEI describes the kaizen process as based on PDCA. Our guide to operational excellence and idea management shows how kaizen, Lean and Six Sigma share that backbone.

Daily kaizen, kaizen event or kaikaku: what is the difference?

The word covers four different things, and mixing them up is a common reason programmes disappoint:

Form What changes Time frame Led by Main risk
Daily kaizen Small fixes in the team’s own area Ongoing, part of the job Operators and team leaders Gains never recorded or shared
Kaizen event (blitz, workshop) One process, a significant change Commonly five days A cross-functional team including the front line Gains fade once the team disperses
Kaikaku A whole value stream, redesigned A planned project Management Bypasses the people who run the process
Suggestion-based kaizen (kaizen teian) Individual ideas, often beyond the person’s own station Ongoing Any employee, answered by a supervisor Ideas left unanswered

Daily kaizen is the base: the operator relabelling a rack, the team leader reordering a checklist that caused mistakes. The LEI warns against relying on events alone, because daily kaizen is what builds problem-solving capability on the front line.

A kaizen event, also called a kaizen blitz or kaizen workshop, is a short, intense project. The LEI’s example is a team building a continuous-flow cell within a week, from learning flow principles to moving machines, testing and standardising. Use one when a process needs a step change that daily kaizen will not reach.

Kaikaku is what the LEI calls breakthrough kaizen, as opposed to gradual, step-by-step kaizen. ISO 9001 draws the same line in its introduction: besides correction and continual improvement, an organisation may need breakthrough change, innovation or re-organisation.

Suggestion-based kaizen is the individual improvement idea: someone notices something, writes it down and expects an answer. Toyota’s 1951 system is the classic example, and the Japanese term is kaizen teian. It works on the same rules as any employee suggestion scheme: a fast answer, a clear owner, a visible result.

Is kaizen the same as Lean, continuous improvement or Six Sigma?

No, though the terms overlap. The quickest way to separate them is by what kind of thing each one is.

Term What it is Scale of change Who does it
Kaizen A practice of small, daily improvement by everyone Small and frequent Everyone, led from the floor
Continuous improvement The umbrella term (ISO 9001 clause 10.3 says continual improvement) Any size The whole organisation
Lean A way of creating value with less waste; MIT researchers coined the term to describe Toyota’s system Whole value streams Leaders design the system, everyone improves it
PDCA A four-step cycle for running one change One change at a time Whoever owns the change
Six Sigma A data-driven method for removing causes of defects and reducing variation Defined projects Trained specialists (“belts”)

Kaizen vs Lean. Lean is the system, and kaizen is how the system gets better. A Lean plant without kaizen has a nice layout that slowly stops fitting the work.

Is kaizen better than Six Sigma? They do different jobs. Kaizen suits the many small problems the people doing the work can see and fix. Six Sigma suits a few stubborn problems whose cause is hidden in data. Where a plant uses both, daily kaizen keeps the process stable enough for Six Sigma projects to mean something.

Which tools do kaizen teams use?

A handful of simple tools do most of the work:

Tool What it is for
Gemba walk Going to where the work happens to see problems first-hand
5S Sort, set in order, shine, standardise, sustain: a workplace where anything abnormal is obvious
PDCA Running each change as a small experiment
Standardised work The written current best method, the baseline for every improvement
5 whys Asking why until you reach a cause you can act on
Improvement board A visible list of open ideas, owners and status

Most kaizen starts on a gemba walk. Our gemba walk checklist has 24 questions and a follow-up template for turning what you see into actions.

What is kaizen called in other languages?

Most languages have their own term alongside the loanword, plus a formal one in the national text of ISO 9001:

  • English: continuous improvement. ISO 9001:2015 names clause 10.3 “Continual improvement”.
  • Swedish: ständiga förbättringar. The Swedish text of ISO 9001 names clause 10.3 “Ständig förbättring”. Produktionslyftet, a national programme started in 2006 by Teknikföretagen and IF Metall, bases its work on Lean and describes it as a chain of ständiga förbättringar.
  • German: KVP, short for kontinuierlicher Verbesserungsprozess, which is usually used as a synonym for kaizen. The German text of ISO 9001:2015 calls clause 10.3 “Fortlaufende Verbesserung”; the 2008 edition said “Ständige Verbesserung”.
  • French: amélioration continue.

For the difference between “continual” and “continuous” and what the ISO clause asks of you, see what continuous improvement is.

What does kaizen look like in practice?

None of these examples needs a budget line, and each ends with a changed standard.

On the shop floor:

  • A shadow board at the press, so every changeover tool has a place and a missing one is obvious.
  • Colour-coded bins for two fasteners that look alike, after an operator picked the wrong one.
  • A changeover checklist written by the operators who do the changeover, with parts staged before the line stops.

In the office:

  • A purchase request form that asks up front for the details approvers always chase.
  • A shift handover template, so the night shift stops rediscovering problems the day shift already knew about.
  • Supplier quality complaints sent to one shared queue with a named owner, instead of to personal inboxes.

For more, see our process improvement ideas by department, and where cost savings hide on a manufacturing floor.

How do you start with kaizen?

Start small and in one place. A pilot area with a willing team leader teaches you more in a month than a company-wide launch.

  1. Pick one area and stabilise it. Kaizen on an unstable process just adds noise.
  2. Write down the current standard. Photos and short steps are enough. This is your baseline.
  3. Go to the gemba with the team. Look at the work together and ask what gets in the way.
  4. Make it easy to raise an improvement idea. A board, a card or a phone, on every shift. Collecting employee ideas compares the options, and getting frontline workers to share ideas covers people without a desk.
  5. Answer every idea quickly, including the ones you turn down. A clear no with a reason keeps people suggesting; silence does not. See giving feedback that builds trust.
  6. Run each change through PDCA and update the standard. An improvement that is not written into the standard quietly reverts.
  7. Count implemented changes and their effect on safety, quality, delivery and cost, not ideas submitted or events held.

When the first area works, widen it. Our playbook for employee-driven continuous improvement covers the step from one team to a whole site.

Should you digitise kaizen?

Not at first. A whiteboard and cards work well for one team in one area, and they keep kaizen visible where the work happens. The trouble starts when ideas cross shifts, teams or sites: cards get lost, follow-up depends on one person’s memory, and nobody can show what changed last quarter.

That is the point to move the list into software. Our guide on how to digitise your kaizen process covers the move without losing the habits that work, and continuous improvement software for manufacturing sets out what a tool must do for operators without a desk. Hives is one option: operators add ideas from a phone, team leads sort them, and implemented changes stay on record.

Why does kaizen stall?

Kaizen rarely fails on day one; it fades. The LEI lists the typical failure modes of kaizen events, and the same patterns show up in daily kaizen:

  • Counting activity instead of results. The number of events held becomes the target, rather than safety, cost, quality or delivery.
  • Gains that do not stick. People drift back to the old way once the event is over.
  • The front line left out. Management runs the event without the people who do the work.
  • Specialists leading. Engineers far from daily operations drive the change instead of frontline managers and operators.

Two more we see often: ideas that never get an answer, which teach people to stop suggesting, and kaizen framed as cost-cutting, which teaches them that suggesting is risky. If your programme has stalled, why continuous improvement is not working walks through a 90-day reset.

Frequently asked questions

What is kaizen in simple words?

Kaizen means improvement. At work it means the people doing a job keep making small, practical changes to it, and each change that works becomes the new standard.

What are the five principles of kaizen?

The Kaizen Institute lists five: know your customer, let it flow, go to gemba, empower people and be transparent. Toyota adds two worth keeping: no kaizen without a standard, and respect for people.

Is kaizen better than Six Sigma?

Neither is better; they solve different problems. Kaizen handles the many small problems people on the floor can see and fix. Six Sigma handles fewer, harder problems whose causes are hidden in data.

What is the difference between kaizen and a kaizen event?

Kaizen is the everyday habit of small improvement. A kaizen event is a focused project, commonly five days long, in which a team makes one significant change to a process. Events work best on top of daily kaizen, not instead of it.

Is kaizen the same as continuous improvement?

Almost. Continuous improvement is the umbrella term. Kaizen is the Japanese practice of it, with particular weight on small steps, written standards and involving everyone from the operator to the plant manager.

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