A secondary battery pack is provided. The secondary battery pack has a structure in which a protection circuit module (PCM) is mounted to a top of a plate-shaped battery cell having electrode terminals formed at an upper end thereof, the PCM includes a printed circuit board (PCB) having a protection circuit formed thereon, a safety element electrically connected between one of the electrode terminals of the battery cell and the protection circuit of the PCB, an external input and output terminal electrically connected to the protection circuit of the PCB, and an electrically insulative module case to cover the PCB and the safety element in a state in which the external input and output terminal extends outside. The PCM is loaded on an upper end case extension portion of the battery cell in a state in which the PCM is electrically connected to the electrode terminals of the battery cell.