An optical switch includes a mirror to reflect an input light; a controller to generate a control signal representing a target rotation angle of the mirror; a generator to generate a low-frequency signal; an adder to superimpose the low-frequency signal on the control signal; a driver to drive the mirror with a drive voltage corresponding to the control signal on which the low-frequency signal is superimposed; a detector to detect a frequency component or a harmonic component of the low-frequency signal included in an output light reflected by the mirror; and a correction unit to correct the control signal based on the detection result by the detector. The generator determines an amplitude of the low-frequency signal according to the target rotation angle.