There is provided an optical axis alignment mechanism between the laser oscillator and the optical fiber. The laser oscillator emits laser light, which then emerges from the emission end of the optical fiber via the axis alignment mechanism. Part of the laser light is received on the light-receiving surface of the CCD camera of a laser light evaluator. Thus, the laser light evaluator acquires a light intensity distribution. The light intensity distribution is used by the optical axis alignment mechanism to align the axis of the laser oscillator with the axis of the optical fiber.