A light-beam-scanning apparatus includes first and second array-light sources including plural light-emitting units and a light-receiving unit; first and second light-source-control units for controlling light emission of the light-emitting units; a write-control unit for controlling the light-source-control units; a deflection unit for deflecting a direction of light emitted from the light-emitting units; and a synchronization-detection element for generating a synchronization-detection signal according to the light deflected by the deflection unit incident onto the synchronization-detection element. Initialization of the light-emitting units of the second array-light source is performed after initialization of the first array-light source is performed; and when the initialization of the light-emitting units of the first array-light source is being performed, a signal for causing the light-emitting units of the second array-light source not to emit light is input to the second light-source-control unit.