Provided is a light source device which includes: a LD (3) mounted on a stem (11); a cap (6) fixed to the stem (11) so as to cover the LD (3); a light converging lens (2) capable of converging light flux emitted from the LD (3); an optical fiber connection portion (16) to which an optical fiber (1) is connected, the optical fiber receiving inputting of the light flux converged by the light converging lens (2); and a holder (7) for holding the optical fiber connection portion (16), the holder being fixed to the cap (6). The optical fiber connection portion (16) includes a position adjusting portion (20) which adjusts a position of the optical fiber connection portion (16) with respect to the holder (7).
