According to one embodiment, a disk device includes a recording medium, a base accommodating the recording medium, the base including a bottom wall, a sidewall on a peripheral portion of the bottom wall, and a rib on a part of an upper surface of the sidewall, a first cover on a part of the upper surface of the sidewall, and a second cover on the rib and above the first cover. The rib includes a first region with a first chamfered surface with a first chamfered width and a second region with a second chamfered surface with a second chamfered width which is less than the first chamfered width. The first region and the second region are located corresponding to a side portion of the recording medium.