An optical switch device is disclosed that includes an optical system deflecting and outputting input light signals using deflector parts; resistor parts provided in corresponding routes for feeding driving signals output from drivers to the corresponding deflector parts; a signal generator part generating a DC signal and an AC signal and feeding the DC and AC signals to the deflector parts through the corresponding drivers and the corresponding resistors; a threshold generator part generating a first threshold and a second threshold corresponding to the DC and AC signals, respectively; a voltage detector part detecting a voltage across each of the resistor parts; and a failure detector part determining whether the deflector parts are normal or out of order based on the corresponding results of comparing the voltages detected by the voltage detector part with at least one of the first threshold and the second threshold.