An illumination light source includes a coherent light source in which a plurality of light emitting points that emit coherent light beams are arranged in a one-dimensional array; and a light magnifying unit that magnifies the coherent light beams that are emitted from the light emitting points so that a diameter of light emitted from the coherent light source in a direction perpendicular to a direction of arrangement of the light emitting points is larger than a diameter in the direction of arrangement of the light emitting points. The illumination light source also includes an optical fiber; and a light-converging optical system in which a magnification is set such that light emitted from the light magnifying unit is coupled to the optical fiber, based on a maximum diameter of the light emitted from the light magnifying unit.