An endoscope light source apparatus includes a first light source section that emits first light, a second light source section that emits second light, and an optical path combiner that combines an optical path of the first light and an optical path of the second light. The etendue of the first light source section is smaller than the etendue of the second light source section. The optical path combiner has an optical deflection surface that deflects the second light, and has an aperture that allows the first light to pass through it within an area of the optical deflection surface. The optical path combiner deflects the second light so that a center axis of the optical path of the second light deflected by the optical deflection surface corresponds to a center axis of the optical path of the first light that has passed through the aperture.