One of the issues that have been raised in civil liability law from the past is the injured person's act and his fault in causing damage to himself and its impact on civil liability lawsuits. The problem is that whenever the injured person has committed a fault in the damage on himself. Although his responsibility is effective or has a role in the damage, in the law of Iran and France, it doesn't cause the injured person to be completely deprived of compensation and doesn't cause the irresponsibility of the perpetrator damage. Still, it also reduces the liability of the perpetrator of the harmful act. In Iranian law, the perpetrator of the harmful act and the injured person share equally in the occurrence of damages. Still, in French law, the extent of the impact of each cause on the occurrence of injuries is the Criterion. This issue is more advanced in Iranian law than in French law due to the rule of action; because the division of liability was accepted from the beginning. Therefore, in this dissertation, by referring to authoritative books and articles in this field, the subject has been studied by analytical and descriptive library methods.