Provided is a steam sterilization device capable of steam sterilization without using a vacuum pump as a mechanism for making the inside of a pressure vessel into a vacuum. The steam sterilization device comprises: the pressure vessel (32) that houses an object to be sterilized, and wherein sterilization occurs using water vapor supplied from steam piping and a vacuum-generating means (34) connected to the pressure vessel (32), and which changes the inside of the pressure vessel (32) into a vacuum state. The vacuum-generating means (34) has: a water ejector (48) a tank (50) that stores supplied water supplied from outside and a pump (52) for supplying the supplied water inside the tank (50) to the water ejector (48).
