Abstract: A laser light source device includes: a laser light source, a first optical device that returns some of a beam emitted from the laser light source so as to induce oscillation at a particular wavelength between some of the beam and the laser light source so that the beam emitted from the laser light source becomes close to a single wavelength, and reflects other portion of the emitted beam, a second optical device that forms an interference fringe from a reflected beam from the first optical device, a beam detection unit that detect a main wavelength of a plurality of wavelengths included in a beam derived from the second optical device and detects an ununiform state of the plurality of wavelengths, a partial reflection mirror that transmits some of the reflected beam from the first optical device to the second optical device and reflects the other portion of the reflected beam toward a recording medium, an optical member that integrally includes the first optical device, the second optical device and the part