A target sensor may include: a plurality of sensor elements, each of the plurality of sensor elements being configured to output a sensor signal that varies in accordance with an amount of light received on a light-receiving surface; and a signal generator configured to process the sensor signals from the plurality of sensor elements. The light-receiving surfaces of the plurality of sensor elements may be disposed at different positions in a second direction different from a first direction along which an image of the target illuminated by the illumination light may move. The signal generator may be configured to compare each of the sensor signals from the plurality of sensor elements with a threshold and output the signal indicating detection of a target to the controller in a case where at least one of the sensor signals from the plurality of sensor elements may exceed the threshold.