A light source module includes a primary optical unit (10) for emitting primary light, a lightconversion unit (20) for receiving the primary light, converting the primary light into secondary light, and emitting the secondary light, a photodetector unit (30) for detecting light, a plurality of optical fibers (40) for guiding light, and an optical branching unit (50), which includes a plurality of primary terminals and a plurality of secondary terminals, for emitting light that is made incident on one of the primary terminals from the secondary terminals, and emitting light that is made incident on one of the secondary terminals from the primary terminals. The primary optical unit and the photodetector unit are arranged on a side of the optical branching unit, on which the primary terminals are arranged, and the lightconversion unit is arranged on a side of the optical branching unit, on which the secondary terminals are arranged, to enable guiding of the primary light from the primary optical unit to the lightconversion unit and guiding of the secondary light from the lightconversion unit to the photodetector unit through the optical fibers.
