An optical scanning apparatus, an image projecting apparatus, and a mobile object. The optical scanning apparatus includes a light source to emit light, a light deflector to deflect the light emitted from the light source at least in a sub-scanning direction to perform optical scanning on a scan region, a light receiver to receive, within a predetermined range in the sub-scanning direction, the light used for optical scanning performed by the light deflector, and a controller to control the light deflector based on a number of times of light reception of the light receiver at a plurality of positions in the sub-scanning direction within the predetermined range. The image projecting apparatus includes the optical scanning apparatus, and a projection optical system configured to project light emitted from the optical scanning apparatus to the scan region.