The invention is to provide a multi-beam light source where the interval of core portions is reduced and the core portions are arranged on a straight line. The multi-beam light source includes a first substrate where a plurality of optical fibers each having a core portion and a clad portion surrounding the core portion coaxially are fixed at predetermined intervals, and a second substrate where a plurality of similar optical fibers are fixed at predetermined intervals. The first and second substrates are put and bonded on top of each other so that the core portion of each optical fiber on the second substrate is inserted between core portions of adjacent optical fibers on the first substrate, and the core portions of the optical fibers on the first and second substrate are arranged substantially on a straight line.