In order to prevent rattling and avoid generation of chips at the time of assembly in a storage case for a power steering control unit of a vehicle, a storage case includes a base having a plate-shaped substrate member, and a box-shaped cover having an opening on the lower side and being mounted on the base so as to cover the upper surface of the substrate member, wherein rattling preventing projections are provided at a plurality of positions on the peripheral edge of the substrate member so as to come into abutment with an opening-side edge of the cover, which is positioned at a mounting position with respect to the base, from the outside; on the inner side of the rattling-preventing projections bevels are formed, which presses the opening-side edge to resiliently deform the peripheral wall of the cover inward and causes a reaction force to act in a direction in which the cover moves away from the substrate member and comes apart from the base; and the opening-side edge is formed with a crimping projection formed by being bent toward the lower surface of the substrate member so as to retain the cover at the mounting position against the reaction force.