A sterilizing material supply apparatus has a sterilizing material gas generator including a mist generation unit and a vaporizing unit. In the mist generation unit, hydrogen peroxide solution in a cup is converted into a mist by ultrasonic vibration generated by an ultrasonic vibrator. The hydrogen peroxide solution which has been turned into the mist is heated by a heater in the vaporizing unit so as to be gasified. The gasified hydrogen peroxide solution is supplied to a workroom of an isolator as a sterilizing gas.