A seat heater provided in a seat cushion of a vehicle seat includes a first heater wire and a second heater wire which are arranged on the opposite side to each other through the groove provided on the surface of a cushion pad, and a groove portion heater wire provided in the groove for connecting the second heater wire with the first heater wire. The groove portion heater wire includes one end portion extending toward a groove bottom beyond a first corner of the groove, the other end portion extending toward the groove bottom beyond a second corner of the groove, and a folded portion folded in the central part of the groove bottom. The extending direction of at least one of the one end portion and the other end portion of the groove portion heater wire is inclined with respect to the depth direction of the groove.