Embodiments of the invention provide a magnetic disk drive having improved vibration characteristics and a reduced size. In one embodiment, a magnetic disk drive comprises: a motor shaft for rotating a magnetic disk; a sleeve for rotatably supporting the motor shaft; and a motor hub into which the motor shaft is press fit. The motor hub supports the magnetic disk and includes a projection portion having an inner surface and an outer surface. The inner surface is in contact with the press-fit motor shaft in directions perpendicular to the rotational axis of the motor shaft. The outer surface faces the sleeve.