To excellently cool a light source with a simple and compact construction and enable effective use of waste heat of the light source.

This light source device 16 is equipped with a pipe mechanism 90. The pipe mechanism 90 is fitted to a bottom plate portion 74 of a casing 72 in which a fluorescent lamp is mounted, and equipped with a heat pipe 92 for absorbing heat of the fluorescent lamp 68, and a frame-like heat pipe 94 that is disposed to face an image pickup panel 22 and discharges the heat absorbed from the fluorescent lamp 68 to the image pickup panel 22a to keep the image pickup panel 22a warm.