This study is to suggest data for setting school uniform size with the size satisfaction degree through finding out the physical body change and uniform size problems following an increase in age during middle school girl days. For this purpose, by analyzing the physical body size data of 13~15 age of girls among $ulcorner$human body size data of the youth for product design$lrcorner$publicized under sponsorship of National Technology Quality Institute in 1999 the physical body size change by part following an increase in age during middle school girl days was found out and the most frequent physical body size by grade was suggested. Questionnaire about uniform production status and product size at the object of uniform makers were measured directly, a school uniform wearing status and size satisfaction degree by part were at the abject of middle school girls were examined by means of questionnaire and unsatisfactory factors in uniform size were found out. Based on collected data the most optimum product size in each part by item were suggested. The method of suggesting the most optimum size suitability by item was decided based on the result of survey into corresponding title and product size by maker and that of survey into the size satisfaction degree of middle school girls by maker, and the product size of maker showing the highest size satisfaction degree was selected as the most optimum product size.