Embodiments of the present invention allow a cover of a magnetic disk drive to be temporarily joined to a base without widening a mounting space, and completely joined after a head disk assembly (HDA) inspection. According to one embodiment, a cover includes a metal plate, an adhesive, and a seal member. The adhesive has a surface wider than the metal plate and the seal member has a surface wider than the adhesive. A solder is coated or printed at an outer periphery of the seal member. A gasket is set at a flange of a base sidewall and an outer peripheral portion of the adhesive of the cover is affixed to an upper surface of the base sidewall to temporarily fix the cover. Low-density gas is injected in a casing interior and a functional inspection of the HDA is performed. After the inspection is finished, helium is injected again, and the casing is completely sealed by melting the solder of the seal member, and joining the seal member to a collar-shaped protrusion of the base sidewall by the solder.