PURPOSE:To prevent a hard disk driving device from being unusable and to prevent a magnetic recording layer from being destroyed as much as possible by discriminating runaway of a voice coil motor by a synchronism detect signal and a track address to immediately stop a mobile coil motor. CONSTITUTION:A track address decoder 22, a synchronism detect signal time-out detecting circuit 24, a new track address latch and shift register 25, an old track address latch 26, a variation detecting circuit 27, a short-circuit using a MOS FET 31, etc., are provided. If the synchronism detect signal is not detected or the detected variation of the track address exceeds a preliminarily set variation, a mobile coil motor 30 is stopped. Thus, the hard disk driving device is prevented from becoming unusable or the magnetic recording layer is prevented from being destroyed as much as possible.
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