Provided is a photoirradiation device that can highly efficiently radiate light at a wire rod by means of a simple structure. The photoirradiation device comprises an insertion path, a reflector, and a light source. The insertion path is for inserting a wire rod. The reflector is shaped like an elliptical arc that has a first focus at a point that is offset by exactly a first distance from the center of the insertion path, and the surface of the reflector that faces the insertion path is a reflection surface. The light source is arranged on the opposite side from the reflector relative to the insertion path and radiates light toward the wire rod. The insertion path is arranged in a position that is offset by exactly the first distance to the light source side relative to the first focus.
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