An HDD has a carriage which moves a head with respect to a medium, and a voice coil motor (VCM) which drives the carriage. The VCM has a magnet, between which and a first shell formed of a magnetic substance a magnetic circuit is formed, and a voice coil which is secured to the carriage and disposed in a magnetic gap. A depression which receives a projecting portion covering a lead of the voice coil is formed in the first shell, and thereby a projection projecting toward the coil is consequently formed. This structure partially narrows the magnetic gap and allows generation of a torque with sufficient intensity.