A light source device includes: light sources； a detector configured to detect light amounts； and a processor configured to: control the light sources to emit light beams by applying a pulse current with a pulse width larger than a predetermined pulse width to the light sources before the processor makes a shift to a strobe observation mode； set a pulse current value at which a ratio of the light amounts of the light beams emitted by the plurality of light sources becomes a predetermined ratio for the plurality of light sources based on a detection result detected by the detector under a state where the pulse current with the pulse width larger than the predetermined pulse width is applied to the plurality of light sources； and make the shift to the strobe observation mode while maintaining the pulse current value for realizing the predetermined ratio.
