A light intensity control device includes light intensity balancing means for balancing the light intensities of the laser beams from the light emitting elements of the laser light source, and simultaneous operating means for simultaneously operating the light emitting elements of the laser light source, wherein the sum of the light intensities of the laser beams from the light emitting elements simultaneously operated by the simultaneous operating means is detected by single detecting means at one time, and is controlled according to the detection output from the detecting means. Accordingly, it is possible to reduce the time required to perform the control of light intensities of laser beams from semiconductor laser elements when the number of the laser beams is increased, thereby more greatly exhibiting the effect of high-speed operation obtained by the increase in number of the laser beams.