Provided is a mirror device including a mirror which is supported to be flappable around a fast axis and supported to be flappable around a slow axis and in which a resonance frequency of flapping thereof with respect to the fast axis is a first value and a resonance frequency of the flapping thereof with respect to the slow axis is a second value lower than the first value; a signal extracting portion configured to obtain from a slow axis coil a synthesized signal including an induced signal generated in the slow axis coil due to an operation of flapping the mirror around the fast axis and configured to extract the induced signal from the synthesized signal; and a signal generating portion configured to generates a driving signal so that the flapping of the mirror with respect to the fast axis is in a resonance state according to the induced signal.