PROBLEM TO BE SOLVED: To provide a sterilizing apparatus capable of suppressing an increase in costs of a peracetic acid based sterilant, and facilitating a concentration control.SOLUTION: This sterilizing apparatus comprises: a chemical liquid tank 3 storing a peracetic acid based sterilant an outward pipe 9 for guiding the peracetic acid based sterilant from the chemical tank 3 to sterilizers 5, 7 a heater 19 provided at the outward pipe 9 to heat the peracetic acid based sterilant and an inward pipe 11 for returning the peracetic acid based sterilant after usage in the sterilizers 5, 7 to the chemical tank 3. The chemical liquid tank 3 is provided with a cooling jacket 31 to cool the peracetic acid based sterilant in the chemical liquid tank 3. The inward pipe 11 is provided with a heat exchanger 17 between the chemical tank 3 and the sterilizers 5, 7, for performing heat exchange with the peracetic acid based sterilant in the outward pipe 9.
