Alight source apparatus comprising a plurality of semiconductor laser devices and a holding member ; each semiconductor laser device comprising: a semiconductor laser element ; a placing body on which the semiconductor laser element is mounted; a substrate on which the placing body is disposed on one side thereof; and a pair of terminals electrically connected to the semiconductor laser element , disposed on the other side of the substrate and protruding from the substrate , the holding member being made of metal material integrally formed, the holding member comprising: a thin-walled section having at least a pair of holes , the thin-walled section being formed by providing at least one depression on a rear side of the holding member ; and thick-walled sections provided adjacent to the thin-walled section on both sides of the thin-walled section, wherein the thick-walled sections have a larger wall thickness than the thin-wall sections, and wherein each semiconductor laser device is mounted on a surface side of the holding member so that the side of the substrate with the placing body of the semiconductor laser device is disposed on the thick-walled sections , and the side of the substrate with the pair of terminals is disposed on the thin-walled section of the holding member and the pair of terminals is exposed through the holes from the rear side of the holding member inside the depression . each semiconductor laser device comprising: a semiconductor laser element ; a placing body on which the semiconductor laser element is mounted; a substrate on which the placing body is disposed on one side thereof; and a pair of terminals electrically connected to the semiconductor laser element , disposed on the other side of the substrate and protruding from the substrate , a semiconductor laser element ; a placing body on which the semiconductor laser element is mounted; a substrate on which the placing body is disposed on one side thereof; and a pair of terminals electrically connected to the semiconductor laser element , disposed on the other side of the substrate and protruding from the substrate , the holding member being made of metal material integrally formed, the holding member comprising: a thin-walled section having at least a pair of holes , the thin-walled section being formed by providing at least one depression on a rear side of the holding member ; and thick-walled sections provided adjacent to the thin-walled section on both sides of the thin-walled section, wherein the thick-walled sections have a larger wall thickness than the thin-wall sections, and a thin-walled section having at least a pair of holes , the thin-walled section being formed by providing at least one depression on a rear side of the holding member ; and thick-walled sections provided adjacent to the thin-walled section on both sides of the thin-walled section, wherein the thick-walled sections have a larger wall thickness than the thin-wall sections, and wherein each semiconductor laser device is mounted on a surface side of the holding member so that the side of the substrate with the placing body of the semiconductor laser device is disposed on the thick-walled sections , and the side of the substrate with the pair of terminals is disposed on the thin-walled section of the holding member and the pair of terminals is exposed through the holes from the rear side of the holding member inside the depression . <EOS>