PURPOSE: To prevent an edge-face reflecting film from creeping to the periphery of an electrode by forming a silicon nitride film on the edge face of a laser- diode element by high-frequency sputtering, to provide the edge-face reflecting film and subjecting an electrode forming surface to dry etching.

CONSTITUTION: Laser-diode bars 1, on edge faces of which edge-face reflecting films composed of a silicon nitride film are attached through a sputtering method, are set to a cathode electrode 8 for a reactive sputtering-etching device, Freon-gas plasma is generated between the cathode electrode and a counter electrode 9, and the laser-diode bars 1 are dry-etched. When etching is conducted under the state, the silicon nitride films adhering on the edge faces are not etched and left from the characteristics of reactive sputtering-etching, and only the silicon nitride films creeping to the electrode side are removed. Accordingly, the silicon nitride films as the edge-face reflecting films creeping to the electrode side can be got rid of completely, and a heat sink and laser-diodes are bonded perfectly, thus also lowering electric resistance, then also reducing thermal resistance.