A receiving portion of a heat releasing member made of metal holds a controller, which is installed to the receiving portion through an opening of the receiving portion. An embeddable portion of the heat releasing member is formed at least along a peripheral edge of the opening of the receiving portion and is embedded in a flange, which is made of resin and covers a hole of a fuel tank. A protective member made of resin may cover each connecting portion between a corresponding one of terminals of the controller and a corresponding one of conductive line members. A primer agent coating may be applied to the conductive line members.