PROBLEM TO BE SOLVED: To provide a steam sterilizer capable of reducing the number of components.SOLUTION: Gas discharged from a chamber 10 flows through an exhaust passage 30. The exhaust passage 30 includes an exhaust inlet end 31 connected to the chamber 10 and an exhaust outlet end 32 opposite to the exhaust inlet end 31. Water discharged from the chamber 10 flows through a drain passage 40. The drain passage 40 includes a drain inlet end 41 connected to the chamber 10 and a drain outlet end 42 opposite to the drain inlet end 41. A connecting part 50 connects the exhaust outlet end 32 and the drain outlet end 42. A common passage 60 includes one end 61 communicating with both the exhaust passage 30 and the drain passage 40 through the connecting part 50 and the other end 62 opposite to the one end 61. An on-off valve 68 is provided in the common passage 60.SELECTED DRAWING: Figure 1
