An illumination unit includes: a light source section including a laser light source; an optical-path branching device outputting light incident from the light source section, by branching the light into an outgoing optical path of illumination light and other optical path; a photodetector receiving a light flux that travels on the other optical path; a control section controlling an emitted light quantity in the laser light source, based on a quantity of the light flux received by the photodetector; and a light-quantity-distribution control device disposed between the optical-path branching device and the photodetector on the other optical path, the light-quantity-distribution control device controlling a light quantity distribution in the light flux to be incident upon the photodetector.