According to one embodiment, a magnetic disk device comprises an actuator, a controller that controls the actuator, a loop shaping filter connected in parallel with the controller, the loop shaping filter having a parameter for suppressing a rotation asynchronous disturbance affecting the actuator, the parameter of the loop shaping filter being determined using a transfer function from an output of the loop shaping filter to before an input of the rotation asynchronous disturbance, and a notch filter that suppresses mechanical resonance of the actuator.