The scientific study of clothing principles may be said to date from about 1930 in Japan, and from about the beginning of the World War II in United States of America. In Japan it was found that when a man wearing a suitable clothing for the season was in a comfortable state, air temperature was about 32°Cand air humidity was about 50% between skin surface and clothing, irrespective of ambient thermal conditions. The scientific study of clothing in United States of America was developed from the information on the temperature regulation of the nude human body.After the World War II, the scientific study of clothing in Japan has been developed based on the basic principles thus far found in Japan and in United States of America.In this paper the development of the scientific study of clothing up to now was reviewed. In addition, the study of clothing which can alter its thermal insulation according to the change of physical activity of subjects or the change of ambient thermal conditions, and the study of the effect of clothing on evaporative heat loss were discussed as the problems to be studied in the future.