An electronic control device has a housing and an air breathing filter assembled to a through-hole of the housing. The air breathing filter has a filter supporting member and a filter cover member. A cylindrical portion of the filter supporting member is inserted into the through-hole from an inside space of the housing, while the filter cover member is fixed to the cylindrical portion of the filter supporting member from an outside of the housing. A pushing portion is formed in a leg portion of the filter cover member for pushing a wall of the housing in a downward direction. A water-proof sealing member is interposed between an inner wall surface of the housing and a flanged portion of the filter supporting member, so that a gap between the housing and the air breathing filter is surely sealed.