PROBLEM TO BE SOLVED: To stop operation of a sterilization process with a condition that air pressure in a sterilization gas decomposition unit is equal to or more than a predetermined value.SOLUTION: A sterilization unit performs sterilization of an object using sterilization gas, and comprises: a path of sterilization gas used in the sterilization process a sterilization gas decomposition unit disposed in the path and decomposing the sterilization gas measurement means for measuring air pressure in the sterilization gas decomposition unit and stop means for stopping operation of the sterilization process with a condition that the air pressure measured by the measurement means is equal to or more than a predetermined value.
