A waveform generator generates an acceleration orbit, a velocity orbit, and a position orbit from the seek time. Each orbits multiplied by respective gains, whereupon the orbits are synthesized by a first adder. The resulting composite orbit is multiplied by a seek distance and then passed through a FIR filter to obtain the target position orbit that is to be applied to the later-stage two-degree-of-freedom control system. The two-degree-of-freedom control system has a characteristic whereby it is able to approximate a second-order low-pass filter.