To propose a novel and improved illuminating device, control method for an illuminating device, and image acquisition system that can adjust each of the light amounts of a plurality of light sources on the basis of the correlation between luminance acquired from a light receiving unit and the light amounts of the emission light beams, and accurately adjust the color temperature of the light receiving unit. The illuminating device includes a plurality of light sources capable of adjusting light amounts of emission light beams, a light monitor unit configured to detect each of light amounts of emission light beams and a control unit configured to control the light amounts of the emission light beams on the basis of a correlation between luminance acquired from a light receiving unit and the light amounts of the emission light beams.