[Problem] To achieve a desired vacuum-drawing ability in a short period using a vacuum pump even when an inexpensive radiator with a low cooling capacity is used. [Solution] The device body is provided therein with: a chamber (2) in which the substance to be sterilized is accommodated a steam generator (5) for supplying heated steam to the chamber (2) a vacuum pump (8) for reducing the pressure inside the chamber (2) a radiator (7) for cooling the medium exhausted from the chamber (2) a first pathway for connecting the chamber (2) with the vacuum pump (8) via the radiator (7) a second pathway for connecting the chamber (2) with the vacuum pump (8) without passing through the radiator (7) and a control unit (10) for switching to the second pathway and exhausting after exhausting from the chamber (2) via the first pathway using the vacuum pump (8).
