A light source device includes: a first light source configured to emit a first source light in a first wavelength range; a source light generator configured to generate, from the first light, a color-varying source light having time varying color; a second light source configured to emit a second source light in a second wavelength range that is different from the first wavelength range; and a light source controller configured to control driving timing for turning on and off each of the first light source and the second light source so as to cyclically select one of the color-varying source light and the second source light to be output as an output source light.