An illuminating light source, and a scanner module and an image scanning apparatus including the same. The illuminating light source includes: a vacuum tube have a cylindrical shape, is filled with a discharging gas, and has a light emitting portion disposed in a lengthwise direction thereof; a discharging electrode disposed upon the vacuum tube, and having a width that increases from a center portion to end portions thereof; and a fluorescent body disposed within the vacuum tube, to absorb first light beams emitted by the discharging gas and to emit second light beams having a longer wavelength than the first light beams, with the second light beams being illuminated through the light emitting portion.