This research is an analysis on the tactics and techniques of four Japanese Judo Champions observed from NHK video tapes of the Olympics 2000, in Sidney with system observing analysis method. It is learned that the major gripping mode of the four Japanese Judo Champions is front grip, and their main moving direction is going forward. Most important of all, their attacking techniques are largely Ashi-waza, and they are mostly B-corner attacks. In addition, their attacking mode is active-quick-rhythm attack and they usually get their Ippon during the first 3 minutes of the game.