Abstract
This report describes control of judo players' weight. In the sports of the weight class system, the weight at the time of applying for the participation to a match often increases or decreases during the conditioning before the match. In the case of judo players of Colleges of Technology in the Tohoku District, there were more rates of increase in weight than decrease. Moreover, the increase and decrease in weight were more often observed in lighter classes than in heavier classes. The conditioning for a player to demonstrate ability to the highest degree in the match concerned, which is known as Peaking, is a very important thing.
