An engine start switch includes, a case member which includes a tubular support portion having an opening portion formed on the front side, a slide member which is slidably supported in a front-rear direction in the inner portion of the tubular support portion, an operation member which is connected to the front side of the slide member, and is movably supported in the front-rear direction in front of the tubular support portion, an annular coil antenna configured to radiate a radio wave signal forward, a wiring substrate which is electrically connected to the coil antenna, and detection means for detecting a rearward movement of the operation member. The coil antenna is attached to the front side of the wiring substrate to configure an antenna substrate assembly, and the antenna substrate assembly is attached to the case member to be positioned between the slide member and the operation member.