Abstract: A modular plug includes a dielectric housing, a plurality of terminals, and a signal transmission cable. The dielectric housing has a cable insertion end, a mating end opposite to the cable insertion end, a lower body portion, and an upper lid portion connected to the lower body portion. The lower body portion extends from the cable insertion end to the mating end. The lower body portion has a plurality of terminal grooves formed adjacent to the mating end, and a cable receiving space extending from the cable insertion end adjacent to the terminal grooves. The upper lid portion is operable relative to the lower body portion to expose the cable receiving space. The terminals are inserted into the cable receiving space through the terminal grooves. The signal transmission cable is received in the cable receiving space, and has a plurality of conductive wires that extend adjacent to the terminal grooves, respectively, and that are connected electrically to the terminals.