judo (jōō´dō), sport of Japanese origin that makes use of the principles of jujitsu, a weaponless system of self-defense. Buddhist monks in China, Japan, and Tibet developed jujitsu over a period of 2,000 years as a system of defense that could be used against armed marauders and yet would not be in conflict with their religion. Jigoro Kano, a Japanese jujitsu expert, created judo (1882) by modifying or dropping many holds that were too dangerous to be used in competition. It depends for success upon the skill of using an opponent's own weight and strength against him, thus enabling a weak or light individual to overcome a physically superior opponent.
A judo match begins with a ceremonial bow, after which each player grasps the other by the collar and sleeve of the jacket, or gi. Points are scored when a fighter successfully executes a variety of throws or immobilizes the opponent for varying lengths of time. Penalties can result in the deduction of points and are called, among other reasons, for throwing an opponent by entwining legs; applying joint locks other than to the elbow; using the arm or hand on an opponent's face; or grabbing the opponent's trousers.
Judo has been an Olympic sport for men since 1964 and for women since 1984. Both fight in eight weight classes. Proficiency in judo is indicated by the color of a player's belt; white indicates a beginner, black a master. There is a wide range of color in between. In 1953 the Amateur Athletic Union recognized judo as a sport and sanctioned annual championships. Numerous schools throughout the world now teach judo. Jujitsu, the unmodified form of judo, has been taught to military and police forces.
See also martial arts.
See K. Kobayashi and H. E. Sharp, The Sport of Judo (rev. ed. 1992).