This method was originally proposed by Akio Toyoda; Later, Toyota Motor Corporation also adopted this method in the process of developing and perfecting its manufacturing methodology. As a part of the introductory course of Toyota production system, this method has become the key content of problem-solving training.

Taiichi ohno, the designer of Toyota's production system, once described the five-question method as: "... the basis of Toyota's scientific method ... repeat it five times, and the essence of the problem and the solution will be obvious." At present, this method has been widely used outside Toyota, and now it is also adopted in continuous improvement method, lean production method and six sigma method.

Extended data:

Realization method

5 Why is it implemented at three levels:

First, why did it happen? From the perspective of "manufacturing".

Second, why didn't you find it? From the perspective of "investigation".

Third, why didn't the accident happen from the system? From the point of view of "system" or "process".

Each level is queried for 5 or n times in a row, and finally a conclusion is drawn. Only by exploring the above three levels of problems can we find the fundamental problems and seek solutions.

Baidu Encyclopedia -5why Analysis Method