A 
polymer battery pack includes: a bare 
cell having main walls and sub-walls; a protection circuit member which is electrically connected to the bare 
cell; a resin sheath which encloses the sub-walls of the bare 
cell in such a way that the main walls are exposed to the outside; and finishing tape attached to the main walls of the bare cell. A frame case may be interposed between the bare cell and the resin sheath. In the 
battery pack, a strong resin sheath and finishing tape or a frame case are engaged with the bare cell, thereby reinforcing the strength of the bare cell and improving the reliability of the bare cell. Also, the 
battery pack does not require a separate space for the supersonic 
welding, and thus can receive a bare cell of 
high capacitance. A method of manufacturing the 
polymer battery pack includes forming a bare cell, forming a core pack by positioning and electrically interconnecting a protection circuit member with the bare cell, and molding a resin sheath accommodating the resin sheath enclosing the core pack and the 
electrode terminals of the protection circuit member are exposed to the outside. A frame case can be formed and engaged with the bare cell to be included in the core pack.