PROBLEM TO BE SOLVED: To provide a heat sterilization method of airborne microbes capable of surely heat-sterilizing microbes contained in air passing through a filter element by equalizing a temperature distribution when heat-sterilizing the air by a heater using a resistance heating type filter element.SOLUTION: The filter element 3 loaded in a cylindrical case body 2 is set to a required sterilizable temperature of 400C° or more, at the same time the periphery of the cylindrical case body 2 is supplementarily heated by an auxiliary heater 4, and the flow rate and pressure drop of the air F passing through the filter element 3 are retained to such levels or more as equalizing the temperature distribution from the central part to the periphery part of the filter element 3, so that the maximum width ΔT of the temperature distribution is controlled to 100°C or less.
