In a semiconductor laser element, a semiconductor laser crystal having a pair of reflection surfaces and a pair of opposing principal surfaces is fused to a heat sink having a planar surface wider than each of the principal surfaces by a layer formed of a fusible metal on the planar surface, whereby one of the ohmic contacts formed on predetermined areas of the principal surfaces is brought into contact with a predetermined portion of the fusible metal layer. A unitary film of an electrically insulating material, such as silicon monoxide, silicon dioxide, silicon nitride, and/or aluminium oxide, is sputtered or otherwise formed continuously on the reflection surfaces and on the exposed portion of the fusible metal layer left uncovered by the laser crystal fused to the heat sink. After the unitary film is formed on the other of the contacts, it is still possible to bond a metal lead directly to the other contact by employing an ultrasonic bonding technique. The fusible metal may be indium, tin, a solder, or a gold-tin, gold-silicon, or gold-germanium alloy, all of which are fusible at a temperature below about 370.degree. C. The laser crystal may be a double or single heterojunction or a homojunction crystal of lead sulfide or telluride or an intermetallic compound, such as GaAs-Al.sub.x Ga.sub.1-x As. The heat sink may be made of silicon, diamond of the IIa type, or copper.