To provide a sterilization device capable of efficiently sterilizing medical wastes.

When performing heating sterilization treatment using steam by a heating device, a sterilization device can sterilize at a temperature higher than a boiling point in one atmospheric pressure by making the inside of a sterilization tank high temperature and high pressure, so as to raise a temperature to 121°C by saturated steam of two atmospheric pressure and, subject to a sterilization treatment for 20 minutes, perform heat sterilization, with the shape of a medical waste retained. However, in a high-pressure steam sterilization (autoclave) treatment, steam is used and a water content may remain there, so that it is difficult to dry the medical waste completely. Consequently, a decompression device and the heating device are combinedly used to heat sterilize and then decompress the interior of the sterilization tank, thus performing drying sterilization.