In a light source device, a control unit causes an energy density of a laser light in a lighting start region RS when a laser support light is maintained to be lower than an energy density of the laser light in the lighting start region RS when the laser support light is put on. For this reason, when the laser support light is maintained, a laser light L is radiated to the lighting start region RS at an energy density of a degree where sputtering does not occur. Therefore, in the light source device, because sputtering in a light emission sealing body can be suppressed, a sufficiently long life can be realized.