Abstract: A device for applying, for a predetermined interval, heated air, which is heated to a pest extermination temperature to a to-be-treated automobile, which is housed in a freely accessible manner in a treatment chamber to exterminate pests inside the automobile includes a circulation fan device arranged in the treatment chamber, a suction part of which is oriented toward the inside of the treatment chamber, a heating member mounted in a discharge part of the circulation fan device, and a rectification member for adjusting the flow direction of the heated air delivered into the chamber via the heating member.