An optical beam scanning apparatus of the present invention includes a body housing; a light source that emits one or more light fluxes; a pre-deflection optical system; an optical beam deflecting device; a sensor that detects a portion of the light flux deflected by the optical beam deflecting device; a holder base fixed to the body housing by a screw; a rotating holder attached to the holder base and provided with a shaft; a sensor substrate fixed to the rotating holder by a screw, the sensor being fixed to the sensor substrate; a rotation adjusting mechanism that rotationally adjusts the rotating holder around the shaft with respect to the holder base; and a fixing mechanism that fixes the rotating holder to the holder base. With this configuration, it is possible to properly adjust deviation of a recording position while making precise rotational adjustment of a horizontal synchronization sensor.