Lean-manufacturing Japan is very happy to be able to publish the first in a series of interviews that will allow us to take a closer look at the Toyota Production System.

Toyota  Production System

An indepth interview with Professor Monden about his renown work, Toyota Production System, and his ideas about Toyota and the spirit of kaizen in today's manufacturing world.

Yasuhiro Monden
Ph.D., Professor
Faculty of Business Administration
Mejiro University
(Professor Emeritus, Tsukuba University)

Part One:

Q. Why did you decide to write the world famous book "Toyota Production System"?

A. Initially I had been a professor of accounting instead of a professor of production management or operations management. In the field of accounting I majored in managerial accounting and then as one of the topics of managerial accounting there was the topic of cost reduction. Someone told me that the Toyota Production System (TPS) or KANBAN system was a very useful way for reducing costs so that's why I visited Toyota and its suppliers to find out about the TPS. I decided to write the book in 1979 but originally, I wrote an English paper entitled "What makes the Toyota Production System Really Kick." That was the first paper systematically written about the TPS. The title was decided on by the editor. Before I sent the manuscript to the publisher of the Industrial Engineering I sent the manuscript to Toyota to get permission to publish it in this United States journal. They have translated my English paper into Japanese to check the content. I still have their Japanese written translation. They gave me permission. Later they said that Mr. Ono checked the contents and by coincidence, it just happens that the other day I was clearing the bookshelves in my office and I found a letter from Mr. Ono. Anyway, when this issue was published in January 1981 there was a very big response throughout the United States. At that time, I was 40 and I was a visiting associate professor of The State University of New York at Buffalo where I was teaching several accounting courses. I received a lot of phone calls at my office in buffalo and I was invited to give many talks at various places about the TPS, in total 10 times in half a year.

Q. Have you ever met Mr. Taiichi Ohno?

A. Yes, I did meet Mr. Ohno. He was said to be a very rigorous person to the managers of the plants but he was very generous and kind to me so I was very happy. He wrote the preface to my TPS book and also published another book on the TPS with me.

Q. When you wrote your book what condition was Toyota in?

A. At that time, there was severe trade friction between the United States and Japan. That was the automobile trade friction and the situation was very similar to the current situation in that the oil price increased and their big cars couldn't be sold but Japanese small cars had good fuel consumption and they sold very well. As a result of this there was a very severe conflict between the two governments and the Japanese automobile makers made the decision to make voluntary restrictions to refrain from exporting their cars to the United States. Of course, they don't have the same situation now. At that time they exported most of their cars but now they have installed their own plants in the United States and their major suppliers have also installed their plants in the United States as well. That's then considered as local content when they use their group plants in the United States.

Q. What was the hardest part of writing the book?

A. Currently, there are numerous books on the TPS but most of them are just describing the kaizen part of the system but the unique point of my book is about the computer-based information systems. In the way for instance that the production information system is used in the MRP (materials requirement planning). In addition, I have written about the technical parts of the system such as the mixed model assembly scheduling techniques (mixed model assembly line), which is called the Goal chasing method. This kind of technical part of the system is very important but no other book has gone into detail about it.

Q. Your book is a very academic and scientific analysis of the TPS. What kind of research did you have to do?

A. Some level of mathematics. This is the field of operations research or industrial engineering and maybe to develop those kinds of techniques you need to study at an engineering school rather than social science or liberal arts departments. In my case I was in the middle of the two.

Q. Did you have any special help from Toyota in writing these algorithms?

A. That was the most difficult part. Some of the technicians and experts at Toyota also belong to various academic associations and sometimes they make presentations there, such as at the academic association of industrial engineering. I'm also a member of this kind of association and when I checked the program and I could see that someone from Toyota was going to give a talk I would attend the lecture and get the information I needed. They not only displayed the manuscripts etc. but they would even write the mathematical models themselves and as the proceedings of the association these would be broadly published.

Q. What is your personal definition of the TPS?

A. I think the most important feature of the TPS is the "Just-In-Time" (JIT) concept. This is the concept of a system to make a product that is needed at the right time, in the right quantity. Many books just emphasize kaizen but JIT is the central part of the TPS.

Q. Which parts of the Toyota Production System do you have the greatest interest in?

A. As an academician I have written many papers on mixed model assembly scheduling models. I have also developed original models and simulation studies that are called heuristics models. That is the part that interests me from an academic view point. However, from a pragmatic point of view, when I visit any plant I always like to see how the single piece flow production is actually being made, even though the units may not be single but small lot production. If this is not being realized then I always suggest how to approach the single piece or small lot production.

Q. For those readers who buy your book, which sections would you recommend they read most carefully and what should they pay attention to when reading those sections?

A. For the beginners, I obviously recommend that they read chapter number 1 intensively. Whilst for those people who have already studied the TPS to some level I would suggest that they read the chapter on how to introduce the system in to their plants. Even although there are various techniques and advanced techniques etc. to be learned there also exists another topic, which is how to actually introduce the system into the plant. There are various steps required to introduce a TPS into a plant and that is another problem, which is not a part of the TPS itself. However, for those responsible for introducing the system it is also a very important topic.

Professor Yasuhiro Monden Ph.D.
Professor Monden, in his Mejiro University faculty office, holds up a copy of the original issue of Industrial Engineering that published his first English paper about the Toyota Production System.

End of Part One . . .

Please click below for Part Two of the Toyota Production System interview.

Toyota Production System: Professor Monden (Part Two)

Interview by Lean Manufacturing Japan editor Warren Harrod

Click below for a list of Professor Mondon's books that are available from


Prof. Monden Book Store of Toyota Production System