Ishikawa Diagram
Developed by Kaoru Ishikawa, this diagram visualises the causes of a problem in a structured fishbone shape. The problem (effect) sits at the right, with major cause categories branching off like fish bones. The most common categories are the 6Ms: Man, Machine, Method, Material, Measurement, Mother Nature (environment). It's a systematic root cause analysis tool that prevents teams from jumping to solutions too quickly.
How to run it
- 1
Write the problem statement (effect) in a box on the right side of the board.
- 2
Draw a horizontal arrow pointing to the problem box — this is the 'spine'.
- 3
Draw 4–6 diagonal branches off the spine, one for each major cause category (use 6Ms, or customise for your context).
- 4
For each category, brainstorm contributing causes and add them as sub-branches.
- 5
Ask 'Why?' for each cause to find deeper root causes (combine with Five Whys).
- 6
Look for causes that appear in multiple categories — these are often the most significant.
- 7
Prioritise 1–3 root causes for action.
Tips
Use the 6Ms as starting categories but relabel them for your context (e.g.
for software: Code, Infrastructure, Process, People, Data, External).
Don't let the categories constrain — add a branch if something doesn't fit.
Variations
Combine with the Five Whys for deeper root cause analysis on individual branches. Run digitally using Miro or Lucidchart for distributed teams.
Where it fits
Frequently asked questions
When should I use Ishikawa Diagram?â–¾
Use Ishikawa Diagram when you want to: Root cause analysis; Quality improvement; Incident post-mortems; Process problem solving.
How long does Ishikawa Diagram take?â–¾
Ishikawa Diagram typically takes 30–60 minutes.
How many participants does Ishikawa Diagram work for?â–¾
Ishikawa Diagram works best for groups of 2–15 participants.
What materials do I need for Ishikawa Diagram?â–¾
To run Ishikawa Diagram you will need: whiteboard or flip chart, markers.
How difficult is Ishikawa Diagram to facilitate?â–¾
Ishikawa Diagram is rated intermediate — some facilitation experience is helpful.
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