To provide an illuminating device for illuminating a desired illumination area with a high volume of light.

To the light source device, in which a light-emitting diode and a clad rod are arranged in a light source box, and then, the clad rod is made extended in an irradiation direction of the diode, and a center axis of the clad rod is made consistent with a light axis of the irradiation light of the light-emitting diode, a light guide made of an optical-fiber strand bundle is connected for receiving the irradiation light from the clad rod.