SEAT HEATER

The seat heater of the present invention comprises: a warming heater (1a) provided in a seat section of a seat; a warming heater (1b) provided in a back section; an overheating-prevention unit (2); and a heating unit (3) that heats the overheating-prevention unit (2), the overheating-prevention unit (2) being configured by a non-return type temperature switch. This configuration allows activating the non-return type overheating-prevention unit prior to reaching an unsafe event, and turns the warming heaters (1a, 1b) OFF reliably, whereby a seat heater with an aim of implementing both high output and safety can be provided.