An optical fiber closure is provided to protect a connected portion of an optical cable and a connected portion of an optical fiber against an external environment. An optical fiber closure includes at least one port adding member(1) between an upper cover(20) and a lower cover(30). The port adding member has an intermediate plate(10) with opened upper and lower portions, and a pair of sealing socket receiving groove(12) and a cable fixing holder receiving groove(13) which are formed on both sides of the intermediate plate. Flanges(15) protrude downward from the cable fixing holder receiving groove of the intermediate plate, and semicircular grooves(15a) are formed upper and lower portions of the flange.
