To provide a polymerization device east to carry and having small size, capable of increasing intensity of light irradiated to a polymerization target, capable of polymerization curing with high accuracy stably, and easy to maintain even when the target contains a monofunctional polymerizable monomer component at low molecular weight which is vaporized by polymerization heat generation during polymerization curing, and the component is adhered and solidified in a device as stains.SOLUTION: By arranging an LED package with heat sink using a plurality of LEDs as a light source in a light source chamber, and coating an outer surface of a light permeable window material for irradiating light ejected from the light source to outside with a protective film, only the protective film can be exchanged when the stains are generated, and labor and cost for maintenance are reduced.SELECTED DRAWING: Figure 2
