A light source device irradiates a material with a first beam, and directs a second beam toward a first position on the material, which is irradiated with the first beam. An alignment mechanism includes an optical unit to allow the first beam to pass therethrough, and to reflect the second beam and direct the second beam in a same direction as the first beam. The alignment mechanism also includes a mirror to reflect the second beam, a beam detecting unit, and a branching unit to receive the first beam which has passed the optical unit and the second beam which is reflected by the optical unit. The mirror adjusts an incident position of the second beam on the optical unit. The branching unit adjusts the first position of the first beam on the material and a second position of the second beam on the material.