An optical signal transmission module is provided, in which a lens surface for condensing light emitted from an LD configured to convert an electrical signal to an optical signal and emit light of the optical signal is integrally formed on an end portion of an optical fiber, a mounting substrate for the LD to be mounted is configured with a specially-shaped substrate, and a fixing portion (a fixing hole portion) for the optical fiber to be fixed is integrally formed on the mounting substrate, at a position where the light emitted from the LD (the light of the optical signal) can be incident on the lens surface.
