Provided is a connection cable between Printed Circuit Boards (PCBs) of a portable terminal having a plurality of PCBs to connect signals of the plurality of PCBs and to connect provided ground planes. The connection cable includes at least one coaxial cable electrically connected between the PCBs for providing a ground plane for a stable high-speed signal interface between the PCBs and a cable connector included in the PCBs for electrically connecting the coaxial cable and providing another ground plane connected to the ground plane of the coaxial cable.