A sterilizing apparatus provides a structure for feeding a sterilizer left in a vaporizing chamber configured to gasify the sterilizer, into a sterilizing chamber, to stimulate a sterilizing action while reducing waste of the sterilizer.The sterilizing apparatus includes a first atmosphere opening valve configured to perform an opening/closing operation to control communication between the atmosphere and the vaporizing chamber for vaporizing the sterilizer before the sterilizer is injected into the sterilizing chamber, and after a sterilizing gas vaporized in the vaporizing chamber is injected into the sterilizing chamber by vacuuming the vaporizing chamber with a vacuum pump, the vaporizing chamber and the atmosphere communicate with each other when the first atmosphere opening valve is opened while the vaporizing chamber and the sterilizing chamber communicate with each other.
