Heat sinks for semiconductor laser devices are manufactured by processing a surface of a panel into a mirror surface, forming a plurality of substantially parallel photomasks spaced at predetermined intervals on the mirror surface, etching the mirror surface through the photomasks to define grooves, the grooves and the mirror surface jointly providing edges therebetween, removing the photomasks from the panel, and thereafter, cutting the panel along the grooves into a plurality of heat sinks. Each of the heat sinks has a surface having a desired ultrahigh level of surface finish accuracy up its edge, and can be manufactured relatively inexpensively.