Abstract: Disclosed is an optical image detector and method for controlling illumination of the same. The optical image detector comprises a light source for controlling the illumination in response to an illumination control signal and irradiating light having the controlled illumination onto a subject, an image sensor for detecting a quantity of light reflected from the subject and generating and outputting image signals corresponding to the detected quantity of light, and an image processor for calculating a shutter-on time using the image signals, comparing the calculated shutter-on time with at least one of maximum and minimum shutter-on times, and generating and outputting the illumination control signal corresponding to values of the compared results.