To minimize unevenness of heating amount in a thermal sterilization device for thermally sterilizing a number of sterilization objects 2 housed in a sterilization tank 1 by spraying hot water within the sterilization tank 1.

In the thermal sterilization device for thermally sterilizing the sterilization objects 2 by housing a number of trays with the sterilization objects 2 being placed thereon in the sterilization tank 1 in a multilayer manner and spraying hot water toward the sterilization objects 2 through an injection nozzle 9 provided within the sterilization tank, the hot water is stored at the bottom of the sterilization tank 1, and circulated and sprayed by blowing steam into the bottom of the sterilization tank. A baffle plate 12 for preventing the steam for hot water heating from directly heating the sterilization objects 2 is provided between a steam blowing portion 13 at the bottom in the sterilization tank and the sterilization objects 2. The baffle plate 12 includes holes for dispersively passing the steam.