Abstract: The present invention provides a thermostat which does not abrade a monitored object, even if movable, and is superior in heat-responsiveness. The present thermostat comprises an approximately round bimetal 3, a holder 2 for holding the lower surface of said bimetal 3 and a cover member 7 for holding the upper surface of said bimetal 3, wherein said bimetal 3 recurves when it exceeds a critical temperature, and said cover member 7 has an opening 7a which does not hinder said cover member 7 from holding said bimetal 3, and portions projecting radially inward from said opening which hold said bimetal 3.