To fully take thermal countermeasures into consideration and decrease cost with superior assembling property by a method, wherein a laser diode and a sub-mount have been formed previously with a solder layer prior to a solder joint, respectively.

Since a function of a absorbing the difference in coefficients of thermal expansion between a sub-mount 1 and a stem 2 is first demanded, an electrode is formed on both faces of an A1N wafer. At the side of a contact face with the stem 2 of the A1N wafer forming this electrode, a solder material such as AuGe, AuSu, or the like is used by an electronic gun(e-gun) or deposition to form a solder layer 3 of a few μm. Next, the A1N wafer, forming this solder layer 3, is cut in a chip-like manner by blade dicing to form a chip. Furthermore, the formed chip is heated and is joined to a prescribed position of the stem 2, whereas the electrode is also similarly formed in an LD 4. After the electrode is formed, the end face is subjected to sputtering to form a sputter film.