NOVELTY - The mounting structure has a pair of rear side elements (11,12) extending in vehicle longitudinal direction and having a front portion (24), rear portion (25), and a rising portion (26). A battery pack (38) is mounted on a vehicle chassis (2) by a sub-frame (51) coupled to respective rear side elements and cross-bar (32). The cross-bar is arranged at a position below a bent portion (27) that connects rising portion and rear portion of rear side elements. The sub-frame has a ring-like support frame (52) that extends in horizontal direction and surrounds outer periphery of battery pack.    USE - Battery pack mounting structure for electric car.    ADVANTAGE - The battery pack can be effectively protected in the event of vehicle rear impact in an electric car in which the battery pack is arranged between the rear side elements arranged at the vehicle rear portion. Since the sub-frame does not include a vertical bent portion, the sub-frame can be formed into such a shape that is difficult to bend in a vehicle vertical direction and difficult to compress in the vehicle-longitudinal length when an impact force is applied to the sub-frame in the vehicle longitudinal direction. Hence the deformation of rear side elements at the bent portions can be suppressed when an impact force is applied from the vehicle rear side, so that the battery pack can be prevented from colliding with an in-vehicle portion arranged in the front.    DETAILED DESCRIPTION - The battery pack mounting structure has a pair of rear side elements extending in vehicle longitudinal direction and having a front portion, a rear portion, and a rising portion. The intermediate portions of respective rear side elements are coupled to each other by a cross-bar that extends in vehicle width direction. A battery pack is mounted on the vehicle chassis by a sub-frame that is coupled to the respective rear side elements and the cross-bar. The cross-bar is arranged at a position below a bent portion that connects the rising portion and rear portion of each of the rear side elements. The sub-frame includes a ring-like support frame that extends in horizontal direction and surrounds the outer periphery of the battery pack. The front side portion (55) and both vehicle-widthwise side portions (53,54) of the support frame are respectively coupled to the cross-bar and the rear portions of respective rear side elements by the coupling portions (62).    DESCRIPTION OF DRAWING(S) - The drawings show a side view of an electric car, and a bottom view of the vehicle rear portion of the electric car. (Drawing includes non-English language text)    Vehicle chassis (2)    Rear side elements (11,12)    Front portion (24)    Rear portion (25)    Rising portion (26)    Bent portion (27)    Cross-bar (32)    Battery pack (38)    Sub-frame (51)    Ring-like support frame (52)    Vehicle-widthwise side portions (53,54)    Front side portion (55)    Coupling portion (62)