To provide a light source device capable of uniforming the illuminance of the exiting end surface of a fiber bundle.

The light source device (20) includes: a light source (21) in which a filament is arranged; a light guide optical system which guides a luminous flux emitted from the light source and includes a first light collecting optical system (23) and a second light collecting optical system (25); and the fiber bundle (29) which is configured by bundling a large number of fiber lines and has an incident end (29A) positioned in the vicinity of the light collecting position (BF) of the second light collecting optical system. The light source (21) is arranged in front of the front focus position (FF) of the first light collecting optical system.