Embodiments of the invention make high-speed rotation of a magnetic disk, suppression of an increase in electric power consumption, and suppression in shaft falling vibration compatible together in a magnetic disk device. In one embodiment, a magnetic disk device comprises a magnetic disk that records information, and a drive unit that rotates the magnetic disk about a shaft. The drive unit comprises a rotary section that holds the magnetic disk, and a stationary section that supports the rotary section through a fluid bearing. The fluid bearing comprises a radial fluid bearing that bears a load in a direction perpendicular to an axial direction, and a thrust fluid bearing that bears a load in the axial direction. The thrust fluid bearing comprises a first thrust fluid bearing having a small diameter and a shallow clearance, and a second thrust fluid bearing positioned outside an outer periphery of a shaft and being larger in diameter and deeper in clearance than the first thrust fluid bearing.