A combined-laser-light source includes: a plurality of semiconductor lasers; an optical fiber; and an optical system which converges a bundle of laser beams emitted from the plurality of semiconductor lasers, and makes the converged bundle of the laser beams enter the core of the optical fiber so that the laser beams are combined in the optical fiber when the laser beams pass through the optical fiber. The optical system is aligned with the optical fiber so that the converged bundle of the laser beams is incident on an area of an end face of the core when steady temperature control is performed on the combined-laser-light source, where the area is concentric with the end face of the core, and has a diameter equal to or smaller than half of the diameter of the core.