The first annular sealing material is filled and applied between a first sealing surface provided on an outer peripheral part of the case and a second sealing surface provided on an outer peripheral part of the cover, a second annular sealing material is filled and applied between a first fitting member provided at the opening of the sealed housing and a second fitting member provided at the outer periphery of the body of the connector housing, a terminal part sealing material is applied to a connection surface which is an inner surface of the wall for partitioning inside and outside of the connector housing and is connected to the circuit substrate, the case and the cover are fastened together by a fastening member, the hermetically sealed housing is provided with a sealable ventilation passage that communicates the inside of the hermetically sealed housing with outside air.