Upon obtaining a detection signal of a shock sensor that detects a shock applied to an apparatus for output, a write disabling unit disables writing by a head on a medium over a predetermined time corresponding to a shock convergence. A determining unit determines, during the write disable, whether an output of the shock sensor is a detection output of the shock sensor due to a shock or an erroneous detection output of the shock sensor due to power supply fluctuations. A sensitivity control unit increases a detection sensitivity of the shock sensor when the determining unit determines that the output is a detection output due to the shock, and decreases the detection sensitivity of the shock sensor and clears the write disable when the determining unit determines that the output is an erroneous detection output due to power supply fluctuations.