Disclosed herein is a secondary battery pack including a battery cell having a cathode terminal and an anode terminal formed at one face having a sealed surplus portion and a protection circuit module (PCM) electrically connected to the battery cell via the cathode terminal and the anode terminal, wherein the PCM includes a board having a cathode terminal connection part connected to the cathode terminal and an anode terminal connection part connected to the anode terminal, and a first case and a second case each having an open face, the first case and the second case being coupled to each other so that the open faces of the first case and the second case are opposite to each other, the board being disposed in a space defined in the first case and the second case through the open faces. The first case and the second case, in which the board is disposed, are mounted to the sealed surplus portion of the battery cell.