Provided is a sheet switch suitable as a sensing mechanism to sense the removal of a subordinate device from a host device. Specifically, the sheet switch is provided with a contact electrode formed in a dome shape with a conductive metal, a counter electrode disposed facing the contact electrode, and a metal sheet made of metal that is disposed on the opposite side of the counter electrode from the side facing the contact electrode with insulating members interposed therebetween. The sheet switch becomes conductive when the contact electrode and the counter electrode touch.