An optical module includes a substrate with a plurality of pairs, which are parallel to each other, spaced in a width direction of the substrate, of optical waveguides formed thereon, each pair being made up of a first optical waveguide that guides a first beam and a second optical waveguide that guides a second beam that monitors the first beam, and a lens that has an incident surface facing at least one pair of the plurality of pairs, collimates, for each of the at least one pair, the first and second beams that emerge from the pair and that differ from each other in at least any one of their incident positions and incident directions on the incident surface, and directs the first and second beams having been collimated and leaving the lens in different directions that depend on the incident positions or the incident directions.