Abstract: There is disclosed an illuminating light source device suitable for illumination at a vibrating place or a portion where an electric lamp is hardly exchangeable for new one, as well as for general luminairs. The illuminating light source device comprises a semiconductor laser element for outputting a laser beam of a particular wavelength in the range from infrared rays to ultraviolet rays, a lens for diffusing the laser beam from the semiconductor laser element and a fluophor for converting the diffused laser beam from the diffusion lens into visible light. Otherwise, the illuminating light source device comprises a group of semiconductor laser elements for respectively outputting laser beams of three primary colors consisting of red, green and blue, a lens for diffusing the laser beam from each of the semiconductor laser elements, and lenses for superposing the diffused laser beams from the diffusion lenses.