PURPOSE: A sterilization method of retort-packed food is provided to firstly and secondly sterilize the food using hot water instead of antiseptics or fungicides. CONSTITUTION: A sterilization method of retort-packed food comprises the following steps: driving a first pump(P1) and opening a first valve(V1) for supplying cold water to an upper tank(110), using a control panel; heating the cold water using steam supplied by opening a second valve(V2); inserting the retort-packed food into a sterilization tank(140); driving a second pump(P2) while opening a fifth valve(V5), a sixth valve(V6), and a seventh valve(V7) to supply the hot water into the sterilization tank for firstly sterilizing; re-heating the hot water inside the sterilization tank with the steam to secondly sterilizing the food; and returning the hot water to the upper tank.본 발명은 식품의 장기 보존을 위하여 포장된 레토르트 식품을 방부제나 살균제를 첨가하지 않고 고온의 물을 통해 단시간에 살균할 수 있는 레토르트 식품의 살균방법으로서, 고온의 물을 통해 1차 및 2차 살균함으로써 살균력이 향상될 뿐만 아니라 간단한 공정으로 단시간 내에 살균을 행할 수 있다.