A laser apparatus may include, a first frame and a second frame, a sleeve through-hole provided in the second frame, a sleeve insertion hole provided in the first frame, a bolt, a positioning sleeve that is formed in an approximately cylindrical shape into which the bolt can be inserted and that positions the first frame and the second frame by passing through the sleeve through-hole and being inserted into the sleeve insertion hole, a nut that is provided in the first frame and into which the bolt is screwed, and a fall prevention unit that is provided in the second frame and that prevents the bolt and the positioning sleeve from falling.