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.