A multiplexer includes: an output section outputting a beam bundle made of a plurality of laser beams whose F-axis directions are aligned; and an F-axis converging lens causing the beam bundle outputted from the output section to be converged in the F-axis direction. Optical axes of the plurality of laser beams constituting the beam bundle outputted from the output section intersect with each other at a single point without relying on the F-axis converging lens.