To provide a light source device capable of efficiently utilizing light emitted from a discharge lamp by capturing the light emitted from the discharge lamp in a wide range as much as possible, in a small light source device.

This light source device comprises: the discharge lamp provided with a pair of electrodes facing to each other, a bulb part including the electrodes, and mercury and a rare gas not less than 0.15 mg/mm3 filled in the bulb part; and a concave reflector arranged to surround the discharge lamp. The light source device is characterized in that the concave reflector is composed by linking a spherical reflector to an ellipsoidal or parabolic reflector, and provided with a hole part in a boundary part linking the two reflectors to each other.