PROBLEM TO BE SOLVED: To control the difference in light volume between illumination lights and to prevent over exposure and under exposure by a simple structure.SOLUTION: A light source device for an endoscope related to this embodiment includes: a white light source for emitting white light beams including first and second wavelength ranges to be used for illumination in endoscopic observation and a rotary filter for sequentially switching between first illumination light having a first wavelength range and second illumination light having a second wavelength range to be taken out from the white light beams. The rotary filter includes: a rotary plate having first and second filter regions arranged in the circumferential direction and a rotational driving part for rotating the rotary plate at constant speed so that the first and second illumination light is switched to each other at the timing of imaging. The first and second illumination light is taken out of the white light beams to be emitted in the first and second filter regions respectively. The size of the second filter region in the circumferential direction is set so that the time integrations of the light volumes of the first and second illumination light emitted per one rotation of the rotary plate are approximately equal to each other.
