In one embodiment, the magnetic disk drive has a magnetic head, an actuator driving the magnetic head, and a control portion controlling a controlled object, including the magnetic head and the actuator, by creating a control signal based on a given target position signal and on a position signal played back by the magnetic head such that the magnetic head reaches a target position. The control portion is so configured that the phase of the open-loop transfer characteristic at the frequency of the resonant characteristics is arctangent ((Rop+1)/Iop) when (a) the resonant characteristics are present at frequencies other than the mechanical resonant frequency of the controlled object in the open-loop transfer characteristics when the control portion and the controlled object are connected, (b) the frequency of the resonant characteristics is higher than the frequency at which the gain characteristic of the open-loop transfer characteristics becomes 0 dB, and (c) the coordinates of a vector locus of the open-loop transfer characteristic at the frequency of the resonant characteristic are given by (Rop, Iop).