NOVELTY - A battery pack comprises: (i) a battery device having a cathode, an anode and a polymer electrolyte, with a terminal from each of the cathode and the anode; (ii) a packaging unit having a first area, carrying a housing recess for accommodating the battery device, a second area and a third area; (iii) a frame mounted around the battery device; and (iv) a connection substrate mounted on the frame and having a terminal unit connected to the terminals.    USE - As a battery pack.    ADVANTAGE - The volumetric increase for the battery pack is suppressed to the smallest possible value without detracting from mechanical strength or reliability of battery terminals. The design may be simplified. The battery device and the battery pack may be produced in an integrated process to diminish processing costs, with the production time being shorter to improve the production efficiency.    DETAILED DESCRIPTION - A battery pack (1) comprises a battery device having a cathode, an anode and a polymer electrolyte, with a terminal being taken out from each of the cathode and the anode; a packaging unit (5) having a first area, carrying a housing recess for accommodating the battery device, a second area formed in continuation to the first area, and a third area formed in continuation to the second area at right angles to the first area; a frame (4) mounted around the battery device; and a connection substrate mounted on the frame and including a terminal unit connected to the terminals. The battery device is accommodated in the housing recess and covered up and bonded to the second area. The terminal unit is adapted to be electrically connected to an external apparatus. The second area, lying opposite to the terminals of the accommodated battery device, is folded back against the first area to cover up a first surface of the batter device, exposed to outside. The first and second areas are then bonded to each other. The terminals of the battery device are connected to the connection substrate. The connection substrate is mounted to the frame. The third area of the packaging unit is folded against the second area to cover up a second surface opposite to the first surface of the battery device, accommodated in the housing recess, and covered up by and bonded to the first area, with the third area. The third area and the first area are bonded to each other.    An INDEPENDENT CLAIM is also included for a method of producing the battery pack, comprising housing the battery device in the housing recess of the packaging unit; folding the second area, lying opposite to the terminals of the battery device, against the first area to cover up the first surface of the battery device, exposed to outside, to bond the first area and the second area to each other; connecting the terminals of the battery device, accommodated in the housing recess and covered up by and bonded to the second area, to the connection substrate provided with the terminal unit adapted for being electrically connected to the external apparatus; mounting the frame around the battery device; mounting the connection substrate on the frame; folding the third area of the packaging unit against the second area to cover up the second surface opposite to the first surface of the battery device with the third area; and bonding the third area to the first area.    DESCRIPTION OF DRAWING(S) - The figure is a perspective view showing an illustrative structure of a battery pack.    Battery pack (1)    Frame (4)    Packaging unit (5)    Opening (41)