The invention provides a structurally simple illumination device capable of safely illuminating the desired area with coherent light. An illumination device (1) includes a laser light source (11) (coherent light source), a light diffuser (14), and a light scanning device (21). The laser light source (11) emits laser beam L (coherent light). The light diffuser (14) diffuses the laser beam L emitted from the laser light source (11). The light scanning device (21) guides the laser beam L to one of the illumination subareas constituting part of an illumination area, thereby scanning the laser beam L radiated from the light diffuser (14) across the illumination area.