Mat rush is an important crop for "Tatami" which is laid on the floor in a traditional Japanese room. Rush stems are woven into "Tatami-omote" which is used as the facing material of "Tatami". According to our life style, it is not too much to say that "Tatami" has built up Japanese people's character and has grown their culture. The materials of quality has been severely required, consequently the production has been specified into the limited places in Japan. The producing system, i. e. the cultivation and post-harvest processing of mat rush, has been established by farmers. However, the theoretical background of the producing system has not been clear, because it has been created by farmers' experiences based on a trial and error. It is urgently required to elucidate this point in order to improve yield in quality and quantity, and to hand down people's wisdom from generation to generation, especially in the present circumstances that well-experienced farmers are disappearing. From this viewpoint, the cultivation technique was analyzed on the basis of the locality of cultivation technique and growth type and the growih characteristics of mat rush in response to environmental conditions. And a principle of mat rush cultivation was extracted, then verified by an experimental cultivation. As to the post-harvest processing technique, the process of quality formation was studied, especially the effect of "Dorozome (procedure of soaking harvested stems in mud before drying them)" on the quality of "Tatami-omote" was analyzed. The analysis on the process of growth and production showed that the most important point in the cultivation was the growth regulation focusing on the developmental phase of individual plant in the middle part of May. The reason was because a state of growth in this season directly determined the number of stems for harvest, and affected their elongation in the following period through crop photosynthesis ruled by canopy structure, subsequently determined the long stem yield. Moreover, the analysis on the locality in cultivation management and growth type revealed that an ideal growth was easily created in the Setouchi area that was the most traditional area in mat rush production, and the locality in the cultivation managements resulted from intending to create the same ideal growth under different climatic conditions. On the other hand, "Dorozome" had an extremely useful effect on producing a specific Sense of touch and looks in "Tatami-omote". However, the characters of harvested stems, which were peculiar to the place of production in Japan, still appeared in "Tatami-omote", even after the stems were processed and woven. These might be a Scientific background supporting the "Tatami-omote" production and sale on description. These results show that the producing system of mat rush has established on the Scientific basis, even though it has created and integrated by farmers' experiences and Senses without any scientific detectors and apparatus. This fact may be very suggestive To us And the results obtained in this study are sure to be the foundations for the Improvement of mat rush production.