A liquid crystal projector for full-color image projection has three LCD panels as light valve device, associated with respectively primary colors, for displaying an image in a color-separated manner. An ultra high pressure mercury lamp illuminates the LCD panels through three illuminating light paths associated with respectively the primary colors. A combining prism combines image light of the primary colors from the three LCD panels, to obtain full-color image light. A laser diode emanates auxiliary illuminating light of a red color among the primary colors according to laser emission, to compensate for shortage in light intensity in the red color. A ferroelectric shaking or vibrating device vibrates the laser diode, to keep visual noise inconspicuous in the auxiliary illuminating light.