A light source device includes a light-emitting device configured to emit laser light, a light-receiving device configured to output a received light signal having an output current according to an amount of received laser light, a drive signal supply section configured to supply to the light-emitting device, a drive signal, and a determination section configured to determine occurrence/non-occurrence of a failure in the drive signal supply section based on one of a drive current of the drive signal and a forward voltage of the light-emitting device, and to determine occurrence/non-occurrence of deterioration of the light-emitting device and/or the light-receiving device based on another of the drive current and the forward voltage and the output current.
