For frequency calibration of a Terahertz (THz) signal at a distant site we developed a THz frequency reference transfer system using an optical fiber link. Transmission of a 2.8THz frequency reference was demonstrated using 51km optical fiber including a 1km actually-laid fiber link, and used for evaluating a phase-locked THz quantum cascade laser. Depending on the condition of the fiber link, the transmitted THz frequency reference degrades. In the case of our 1km fiber link, imposed noise was negligibly small (10−15 level), having an adequate accuracy to calibrate the distant THz frequency standard.