Embodiments in accordance with the present invention provide a magnetic
disk drive capable of alleviating an adverse effect of vibrations
inherent to a housing on positioning control, reducing the adverse effect
over other frequency range, and stabilizing the positioning control. In a
magnetic disk drive according to embodiments of the present invention, a
position control circuit that controls the position of a magnetic head
produces a signal, based on which the position of the magnetic head is
controlled, according to positional information read by the magnetic
head. The signal is transmitted via a multi-rate filter circuit that
decreases a sensitivity function relevant to a predetermined object
frequency by a first predetermined gain, and suppresses an increase in
the sensitivity function relevant to frequencies lower than the object
frequency to a second predetermined gain.