To provide a light source device in which irradiation light beams from a plurality of light emitting diodes are efficiently made incident even on a light incident port having a small diameter of an optical fiber bundle.

The device is provided with an optical fiber bundle, a reflection body which is arranged in front of a light incident port that is provided on one end of the bundle and a plurality of light emitting diodes. The body is provided with a conical surface shaped reflection surface opposing to the port with a prescribed tilt angle. The plurality of light emitting diodes are arranged at the outer periphery of the reflection surface and the irradiation light beams from the diodes are made incident on the light incident port of the axis end of the fibers in an approximately perpendicular manner through the reflection surface.