A semiconductor laser is constituted by a die pad and a plurality of leads formed by a plate-shaped lead frame that are integrally supported by a resin portion made of a mold resin, and a laser chip is mounted thereon through a sub-mount. The die pad and the tips of the leads are not subjected to forming processes, with the resin portion being formed on both of the surface and rear surface of one portion of the lead frame, while most of the rear surface of the die pad is exposed without being coated with the resin portion, and a fin for positioning and/or heat-radiating whose surface and rear-surface are exposed without being covered with the resin portion is formed on each of side portions of the die pad. With this structure, it becomes possible to provide a resin-mold-type semiconductor laser which accurately carries out a positioning process upon being attached to a housing or the like, and sufficiently carries out heat radiation, while improving adhesion between the lead frame and the resin.