To provide a photopolymerization device suitable to be used for filling photopolymerization resin into position of a root bored hole for sealing the root bored hole.

In the photopolymerization device main body 1, a light source, a reflection mirror, a filter, etc., are included, a light conductor is freely attachably and detachably installed on the photopolymerization device main body 10 through a nozzle part 16 of the photopolymerization device main body 10, and when it is installed, its end part is fixed at a focal position of the reflection mirror in the photopolymerization device main body 10. A photopolymerization resin filled to a root bored hole position is hardened by light emitted from a tip 20b of the light conductor as it is inserted into a root tube.