A timer includes: a case body made of synthetic resin; an outer case made of synthetic resin, located above the case body and extending to a portion of an upper face of a watch glass; a reinforcement member made of metal embedded in the case body to prevent deformation of the case body when the watch glass is fit thereto and ensure airtightness; and an antenna arranged inside the case body and beneath the reinforcement member, wherein the reinforcement member is embedded in the case body in no electrical continuity with a ground potential.