An illumination device includes a substrate including a fluorescent layer, and capable of rotating around a predetermined rotary shaft, a light source adapted to emit an excitation light adapted to excite the fluorescent layer, and a control device adapted to control emission of the light source so that, when the substrate is rotating, a first area of the fluorescent layer is irradiated with the excitation light in one round, and at least a part of the first area is not irradiated with the excitation light in another round.