A connection FPC 75 and a sheet heater 30 are joined together with a solder joint member interposed therebetween. The connection FPC 75 includes a ground contact point 90b and a connection electrode 90d extending along a row of contact points and to which the ground contact point 90b is connected. The connection electrode 90d extends beyond both ends of the row. The sheet heater 30 includes a ground land 46b and a connection land 46d extending along a row of lands and to which the ground land 46b is connected. The connection land 46d extends beyond both ends of the row.