A laser device is provided with: a plurality of light source elements that individually output laser beams; a wavelength selection means for selectively transmitting light of a designated wavelength band, said wavelength selection means being positioned in the optical path of the laser beams; and a partial transmission reflection body positioned such that light transmitted by the wavelength selection means is inputted, a portion of the inputted light being reflected toward the wavelength selection means, and the remainder being transmitted. The wavelength selection means selectively transmitsa portion of the laser light outputted from the light source elements. The partial transmission reflection body reflects a portion of the transmitted laser light. The wavelength selection means transmits a portion of the reflected laser light, and returns said reflected laser light to the light source element from which said light was outputted, whereby the light source elements oscillate with priority at a wavelength within the wavelength band transmitted by the wavelength selection means.