The endoscope light source device includes a semiconductor light source, optical fibers that are inserted into an endoscope, guide first light beams from the semiconductor light source, and are arranged in plural rows in at least an angle portion of the endoscope, an optical coupling circuit that is arranged at a distal end side of the endoscope with respect to the angle portion, and couples the first light beams guided by the optical fibers arranged in the plural rows to obtain a coupled light beam and a wavelength conversion part that is arranged at a distal end side of an endoscope insertion section in the optical coupling circuit, and converts a part or all of the coupled light beam from the optical coupling circuit into a converted light beam having a given wavelength by a phosphor.
