The present invention provides safety technique for a high pressure steam sterilizer, namely a dual safety unit is used to hold a close state of a lid for opening and closing an opening of a horizontal inner cavity, and objects are sterilized in high pressure steam the invention also provides a technique for ensuring safety when the high pressure steam sterilizer is initiated, namely a lock unitfor locking a close state of the lid and a detection switch thereof are provided, and the sterilization operation is not performed when the detection switch does not detect the lock state. The high pressure steam sterilizer is provided with a lock plate, arranged on the circumference of the opening of the inner cavity and rotating toward one side by a motor such that a lock rod enters a fixed sidelock part and a lid side lock part to hold the lock state of the lid electromagnetic valve for stopping the lock plate, a lock position detection switch is used to detect that the lock plate rotatesuntil the lock state and a plunger piston protrudes such that the lock plate rotates until the stop state, and the sterilization operation may be performed by the protruding detection of the plungerpiston.
