Disclosed is a data storage device, a servo control method, and a program
to reduce effects of a resonance frequency of an actuator or the like without reduction
in servo control performance. A band-pass filter comprising a first all pass filter
(APF) and a second adder, a second APF, and a multiplier are used to detect how
much a current resonance frequency of the actuator deviates from a set value of
a center frequency of the first APF, and based on a result of the detection, the
center frequency of the first APF is properly adjusted. The adjustment of the center
frequency of first APF enables a center frequency of a notch filter comprising
the first APF and a first adder to be automatically approximated to a current resonance
frequency of the actuator.