An optical scanning device includes a beam generating unit configured to generate a beam of light, a scanning unit with a plurality of scanning planes configured to deflect the beam of light generated by the beam generating unit and cause the beam of light to scan an image carrier in a main-scanning direction, a micro mirror configured to deflect the beam of light generated by the beam generating unit and thereby enable the deflected beam of light to fall on the scanning unit, a position detecting unit configured to detect a position of the beam of light deflected by the micro mirror, an input voltage control unit configured to control an input voltage value for inclining the micro mirror and thereby causing the beam of light to deflect, and an input voltage determining unit configured to control the input voltage value controlled by the input voltage control unit.