The "Washlet G"(Toilet Seat with Shower Unit), which is authorized by the "Mechanical Engineering Heritage" of the Japan Sciety of Mechanical Engineers, is said to have revolutionized Japanese toilet environment and custom. However, its success was indivisible from the diffusion of seat-type toilet bowls (so called "western type toilet bowls"), and the diffusion of flush toilets. This paper presents the history of development of Japanese flush toilet. First, efforts for domestic production of the western style toilet bowl are introduced. Next, the change of the Japanese flush toilet products and growth to the manufacturer of the World's standard product are described. Finally, the present situation on the toilet including the Washlet and their future are mentioned.