The growing interest in time-use study has led to rapid increases on the global level as a tool to make the unpaid work and gender disparities visible. Recently, many countries in ESCAP region have been making efforts in time-use study. The present study aims to compare “Participation Rate in Activities” among the three countries of Thailand, Cambodia and Japan from the gender aspect. The data was obtained from “The Time Use Survey 2001” by the National Statistical Office of Thailand, “Cambodia Socio-Economic Survey” by the National Institute of Statistics of Cambodia, and “The 2001 Survey on Time Use and Leisure Activities” by the Statistics Bureau of Japan. The new four time-use classifications were applied to the comparison. The results of the study are as follows : (1) The classification employed by the Thai and Cambodian authorities had items and array that are different from the Japanese and Eurostat's counterparts. (2) The tendency of gender difference among the three countries was similar in Participation Rate in Activities. (3) The quality of both the Thai and Cambodian surveys needs to be enhanced.