<p>The group III-V compound semiconductor laser can emit light in a 1.3 mu m band or a 1.55 mu m, and has a laser structure including an active layer (5) for emitting light, guide layers (6) sandwiching the active layer and having a band gap larger than the active layer, and clad layers (7) embracing the guide layers and having a band gap larger than the guide layers. The lattice constants of the guide layers and clad layers are larger than a1 by 0.5 % or more and smaller than a2 by 0.5 % or more, where a1 represents the lattice constant of GaAs and a2 is the lattice constant of InP. The semiconductor laser of a 1 mu m band having an excellent conversion efficiency and a high characteristic temperature. <IMAGE></p>
