Since the absorption of a fundamental wave by a fiber increases if it is tried to obtain a wavelength conversion light of watt-class high output, the fiber length needs to be shortened. However, since oscillation efficiency conversely decreases if the fiber length is shortened, it is difficult to obtain a high-output fundamental wave. Thus, by reflecting an excitation light incident on the fiber in the fiber, the excitation light is efficiently absorbed to amplify the fundamental wave with a high gain. Further, by shortening the fiber length, the absorption of the fundamental wave is also reduced to improve a fundamental wave output. Consequently, a wavelength converter capable of ensuring a stable high output up to watt-class is achieved.