An illumination device having a first light source, a second light source, whose luminous color differs from that of said first light source, and a controller for controlling the illuminating condition of each of the first light source and the second light source is configured. The controller turns on the first light source so that the light intensity of the first light source gradually increases at an early stage of a turning-on operation. Moreover, the controller turns on the second light source when the light intensity of the first light source gradually increases after a lapse of a predetermined time from the start of the turning-on of the first light source.