An optical scanning device comprising: a mirror portion that has a reflecting surface on which an incidence ray is reflected; a first actuator that causes the mirror portion to swing around a first axis which is in a plane including the reflecting surface at a time of a standstill of the mirror portion; a second actuator that causes the mirror portion to swing around a second axis which is in the plane including the reflecting surface at the time of the standstill of the mirror portion and intersects with the first axis; a first angle detection sensor that outputs a signal corresponding to an angle of the mirror portion around the first axis; a second angle detection sensor that outputs a signal corresponding to an angle of the mirror portion around the second axis; and at least one processor, wherein the processor is configured to provide a first driving signal having a first driving frequency to the first actuator, and provide a second driving signal having a second driving frequency to the second actuator, characterised in that the processor is further configured to derive a first average phase delay time by averaging a first phase delay time of the output signal of the first angle detection sensor with respect to the first driving signal in a plurality of cycles, derive a second average phase delay time by averaging a second phase delay time of the output signal of the second angle detection sensor with respect to the second driving signal in a plurality of cycles, generate a first reference signal representing that the angle around the first axis is equal to a reference angle based on the first driving signal and the first average phase delay time, and generate a second reference signal representing that the angle around the second axis is equal to a reference angle based on the second driving signal and the second average phase delay time. a mirror portion that has a reflecting surface on which an incidence ray is reflected; a first actuator that causes the mirror portion to swing around a first axis which is in a plane including the reflecting surface at a time of a standstill of the mirror portion; a second actuator that causes the mirror portion to swing around a second axis which is in the plane including the reflecting surface at the time of the standstill of the mirror portion and intersects with the first axis; a first angle detection sensor that outputs a signal corresponding to an angle of the mirror portion around the first axis; a second angle detection sensor that outputs a signal corresponding to an angle of the mirror portion around the second axis; and at least one processor, wherein the processor is configured to provide a first driving signal having a first driving frequency to the first actuator, and provide a second driving signal having a second driving frequency to the second actuator, provide a first driving signal having a first driving frequency to the first actuator, and provide a second driving signal having a second driving frequency to the second actuator, characterised in that the processor is further configured to derive a first average phase delay time by averaging a first phase delay time of the output signal of the first angle detection sensor with respect to the first driving signal in a plurality of cycles, derive a second average phase delay time by averaging a second phase delay time of the output signal of the second angle detection sensor with respect to the second driving signal in a plurality of cycles, generate a first reference signal representing that the angle around the first axis is equal to a reference angle based on the first driving signal and the first average phase delay time, and generate a second reference signal representing that the angle around the second axis is equal to a reference angle based on the second driving signal and the second average phase delay time. derive a first average phase delay time by averaging a first phase delay time of the output signal of the first angle detection sensor with respect to the first driving signal in a plurality of cycles, derive a second average phase delay time by averaging a second phase delay time of the output signal of the second angle detection sensor with respect to the second driving signal in a plurality of cycles, generate a first reference signal representing that the angle around the first axis is equal to a reference angle based on the first driving signal and the first average phase delay time, and generate a second reference signal representing that the angle around the second axis is equal to a reference angle based on the second driving signal and the second average phase delay time.