According to one embodiment, a disk device includes a plurality of magnetic disks, a casing, a column, a rotary component, and a screw. The casing includes a base having an inner space in which the plurality of magnetic disks is accommodated, and a first cover attached to the base to close the space. The column with a screw hole, is located in the space and is attached to the base by being fitted into a recess formed in the base. The rotary component is located in the space, surrounds the column, and is configured to rotate about the column. The screw is fitted into the screw hole through the first cover.