According to one embodiment, a disk drive includes a housing comprising a base and a top cover combined to the base. The housing contains a motor configured to rotate about a rotational center and a pivot as a rotational center of a head actuator. The top cover includes a first rib. The first rib is configured in a shape comprising a first center in a triangular region. The triangular region has vertexes on a first point corresponding to the rotational center of the motor, a second point corresponding to the pivot, and a third point at a central portion of one side on an opposite side of the second point with respect to an axis extending longitudinally relative to the housing through the first point.