A mirror driving circuit applies a voltage to drive a mirror and switches an optical path of light output from a channel of an input port to a channel of an output port. The mirror driving circuit includes an offset-voltage applying unit that applies an offset voltage to the mirror, an applied-voltage determining unit that determines an applied voltage to be applied to the mirror based on a relation between the channel of the input port and the channel of the output port forming a path of the light, and a voltage applying unit that applies to the mirror a remaining voltage obtained by subtracting the offset voltage from the applied voltage.