Recently there has been observed a change of farmers' lives in Japan. Many young farmers had moved to big cities in order to get higher incomes, but they have been coming back to their villages because they can engaged in modernized agriculture, such as the development of vinyl-tent-house for various products. The author examined the actual status of the workers working in vinyl-tent-houses at a district of Kochi prefecture in Japan and also investigated their working conditions and environment. Vinyl-tent-houses are divided into four types by their sizes and utilization. A-type has heater but no ventilation. B-type has both heater and ventilation and this size belongs to the most common type. C-type has not heater nor ventilation and is an old fashion type. D-type is modern and large in size, and has both heater and ventilation. Results are as follows: (1) Differences of working environment could be observed among the four types.(2) About a third of the workers have experienced histories of acute poisoning by chemical substances used for agriculture. (3) There were not observed many cases of "farmers' syndrome" named by Wakatsuki. According to these results, the author concludes that occupational hazards by works in vinyl-tent-houses are unable to evaluate by the method maintained by Wakatsuki.