As results of analyzing judicial precedents about infection in hospitals in connection with mistakes and causality in medical litigations shows that the Mitigation of Law Principles To Prove responsibility in medical litigation has not been able to play its role compared to its intended purposes. And Major sentiment from those judgments is that a mistake can't be proved only by the fact that certain infection in hospital occurred in connection with hospital infection. Therefore, the number of indirect facts to deny estimation is overwhelmingly high. Like this, especially for hospital infection which is difficult to prove indirect facts themselves to estimate mistake, major sentiment from those judgments have a problem that impute sharing of losses caused by hospital infection to patient. In accordance with the Principles of equitable and proper sharing of losses, it's required to prepare legal interpretation and theoretical methods to largely mitigate patient's responsibility to prove medical mistakes compared to other medical litigations in connection with existing Mitigation of Law Principles To Prove responsibility and conventional theory of estimation. In connection with this, the results of review that duty of safety management in hospital infection cases can be the base of conversion of proving responsibility, the duty that prevent hospital infection, corresponding the duty of safety management in hospital infection is not conventional duty of safety management based on duty of good faith but secondary obligation of medical contract. The breach of duty preventing hospital infection is the violation of medical contract, but there is no logical necessity that convert proving responsibility from the obligation of contract itself. Therefore, the duty of preventing hospital infection from the obligation of medical contract, corresponding the duty of safety management in hospital infection cases cannot be the base of conversion of proving responsibility alone. But, it's still required to conversion of proving responsibility in hospital infection, we need further studies on cases of Germany which applies legal estimation of proving responsibilities in hospital infection.