Improving the lifetime of an integrated semiconductor laser diode module into which a GaN semiconductor laser diode and a GaP semiconductor laser diode are integrated, and the lasing properties of the laser diodes. Prior to a joining step of an LD 1 wafer that is made of a nitride semiconductor structure formed on a GaN substrate and an LD 2 wafer that is made of an aluminum gallium indium phosphide semiconductor structure, a facet of a resonator of the nitride semiconductor structure is formed by etching. A facet of a resonator of the aluminum gallium indium phosphide semiconductor structure is formed, after the joining step, by cleaving. The wafers are joined so that the facets of the resonators of the nitride semiconductor structure and aluminum gallium indium phosphide semiconductor structure are out of alignment in a lengthwise direction of the resonators.