An illumination device of the invention includes a light source unit including light emitting devices having light emission surfaces, a collimating system having collimating lenses provided to respectively correspond to the light emitting devices of the light source unit, into which lights from the respective light emitting devices enter, a collecting lens into which the lights output from the collimating lenses enter, and a rod lens having a light incident end surface into which the light collected by the collecting lens enters. The light source unit and the collimating system are adapted so that a principal ray of the light output from the light emission surface corresponding to a part of the light emitting devices of the light source unit may enter a position separated from an optical axis of the collimating lens corresponding to the part of the light emitting devices of the light source unit.