A thermoswitch in which two fixed terminals are provided to a base disposed in a bottomed housing and a movable contact mechanism is provided between the two fixed terminals so that the movable contact is connected or disconnected by the displacement of a thermosensitive member such as bimetal, wherein the basal portions of the fixed terminals projecting from the base after solidifed with a first resin and a recess formed by the housing and base is filled and solidified with a second resin such that lead wires connected to the fixed terminals are embedded in the resin. According to this device, penetration of water coming down along the lead wires is positively prevented by the two resin layers.