The illumination device capable of illuminating plural regions via a light diffusion element includes a laser light source that emits a laser beam, an optical scan unit capable of changing an optical path of the laser beam from the laser light source, an optical path adjustment element and a light diffusion element. On the optical path adjustment element, the laser beam from the optical scan unit is incident, an incidence position of the laser beam varies depending on the optical path determined by the optical scan unit; and an emission angle of the laser beam varies depending on the incidence position. The light diffusion element diffuses the laser beam and emits diffused light. On the light diffusion element, the laser beam from the optical path adjustment element is incident and an emission angle of the diffused light varies depending on an incidence angle of the laser beam.