The ice hockey which is called as a flower of winter sports stimulated many spectator s excitement with tough physical fight and speedy, dynamic game lead. But because of sports injury and accidents of players caused by frequent physical fights during a game, the seriousness of its problem was raised now. These kind of violence act becomes worse because of unwritten rule which was not written, but being recognized and kept unconsciously by coaches and players. The coach and player have a duty to prevent violence act and violation of rule beforehand, which could happen during game, by correctly understand and well-acquainted with game rules, and the Korea Ice Hockey Association has a duty to place punishment like warning, leave and suspension seriously according to player s intention on sports injury and violation of the rule, which happened during game, in the relation with rule they established after confirmation if they kept game rule, and this is for fair and safe game. But because of unwritten rule which has been kept unconsciously between players and players, players and judges in ice hockey, many players get frequent injuries and aftereffects after retirement, and criminal liability could be placed on intended violence beyond simple violation of rule. They do intended violence act when the spirit of their team is lowered down, they need to change flow of a game or team goalie was checked, they fight with fist and without any equipment, and judge doesn t involve right away but involves after a player is fell down etc., and these unwritten rule is not only the act which is not harmonize with sportsmanship but something also that must not be allowed on ice according to the spirit of sports. If we take a look of game rules written by Korea Ice Hockey Association, even though the physical fights happen frequently, which cause player s injury, the punishment on it is not much serious, so it is become a issue. And among many violation of the rules, heavy punishment is laid on the player if he doesn t obey the judge s restriction, this means that the role of judge is important. The content of ice hockey s unwritten rule, which was reported by media, was reestablished and classified as danger of injury and unconsciously recognized rule between players, and cases of various violence act related to unwritten rule and also various accidents and injuries which would be caused by this were presented, and the need for systemization of ice hockey rule was suggested in this study.