PURPOSE: To search for the target position of signal recording tracks in a short period of time by controlling the number of revolutions of a spindle motor in accordance with the difference between the number of spindle motor revolutions of a search originator and a search destination.

CONSTITUTION: During a start of a spindle motor 8, a microcomputer 9 sends an instruction to a PLL circuit 3 so as to make the pulse width of phase difference signals (MDP) to a prescribed period H and starts the rotation of the motor 8. Moreover, in accordance with the program written in a ROM 11 and the signals from a key input device 10, a RAM 12 is used for the operations so as to control the entire device and performs a mode switching of the circuit 3. By supplying a current to the spindle motor for the amount of current-time product which is equivalent to the angular momentum change which corresponds to the difference between the number of revolutions of the motor 8 of the search originator and the search destination, the speed of the spindle motor is increased or decreased so that the speed of the track being seeked is kept at a target speed.