Provided is a laser welding device using a laser to fuse resin material parts to each other, and more particularly, a thermosetting resin laser welding device fixing a fusion target by using a transparent fixing member to perform fusion while a laser is emitted to an exact fusion point, and capable of emitting the laser to the fusion point by using a refraction of the laser even when an obstacle is present in a straight line between a laser light source and the fusion point.