Laser diode module, laser apparatus and laser processing apparatus

Submount substrates (602) are connected to both sides of a laser diode (601) via hard solders (603). The lower submount substrate and a heat sink (605) are connected together by a soft solder (606). The heat sink and a presser electrode (608) are fixed with a predetermined gap therebetween via an insulating spacer (609). A coil electrode (607) is fitted in a V-shaped groove of the presser electrode. As the coil electrode is deformed slightly elastically, the coil electrode is pressed against the upper submount substrate (602).