An optical scanner is provided including a light source configured to emit light, a light source driving device configured to drive the light source, a light deflector having at least one rotating reflection plane and configured to deflect the light emitted from the light source to a scanning area, and a light detector configured to output a signal to control a timing at which scanning of the scanning area by the light deflected by the light deflector starts, where the light detector and the scanning area are sequentially scanned in a single scanning by one reflection plane of the light deflector, and the light source driving device drives the light source using a first driving method when the light scans the light detector, and drives the light source using a second driving method that is different from the first driving method when the light scans the scanning area.