To enable to obtain a reliable effect of heat sterilization in a heat sterilizing device for a cutter for agricultural and horticultural crops by combusting a liquefied gas, and a simple structure of the device.

The tip part 3 of a blade is heat sterilized by flameless combustion of a mixed gas with a catalyst by guiding the mixed gas from a liquefied gas cartridge 4 combined in a grip part 2 to a thin metal pipe 8 held in a channel formed at the tip part 3 of the blade as a gas flow passage, combining a combustion reaction catalyst 10 and an electric heater wire 9 covered with a heat accumulation ceramic material in the gas flow passage 8, and heating the mixed gas by the electric heater wire 9 to heat the combustion reaction catalyst 10 at the temperature for initiating the combustion of the catalyst.