Embodiments in accordance with the present invention improve bonding reliability in a feedthrough sealing portion. According to one embodiment of the present invention, an opening of a through hole is provided on the bottom of the base of the magnetic disk device and a feedthrough mounting plane which is one of the steps formed toward the outside of the device is provided around the opening. The feedthrough includes a flange and pins which are fixed to the flange by a glass material and pass an electric signal. The flange is larger in outer shape than the opening of the base. The periphery of the flange of the feedthrough is mounted on the feedthrough mounting plane of the base from the outside and bonded thereto by solder.