Abstract: A photocoagulator for guiding a semiconductor laser beam to an eye to be treated for a photocoagulation operation. The photocoagulator comprises a main device for incorporating first semiconductor laser light sources, an auxiliary device for incorporating second semiconductor laser light sources, an optical fiber for guiding to the auxiliary device output beams from the first semiconductor laser light sources incorporated in the main device, a combining optical element disposed in the auxiliary device for combining the output beams from the first semiconductor laser light sources and the output beams from the second semiconductor laser light sources into a combination beam, and a beam guide optical system for guiding the combination beam combined by the combining optical element to the eye to be treated. The photocoagulator having such an arrangement is made compact and can emit a laser beam having a sufficient energy level.