A top plate unit includes a top plate on which an object to be heated is placed, an underframe for holding the top plate placed on an upper surface thereof, the underframe being adapted to be placed on an upper surface of a kitchen counter in a manner in which a lower surface of the underframe is held in contact with the upper surface of the kitchen counter, and a decorative panel 6 for covering an upper portion of an outer peripheral edge of the top plate. The decorative panel has an inwardly bent portion that has been formed by bending an outer peripheral edge portion of the decorative panel inwardly toward a lower surface of the underframe to hold the outer peripheral edge of the underframe.