A battery frame that supports a bottom of a battery pack mounted under a floor panel includes a plurality of first cross members extending along the vehicle width and having opposite ends coupled to the floor side members to thereby support the bottom of the battery pack, a second rear cross member coupled with a rear cross member and extending along the vehicle width to support the bottom of the battery pack, and first side members and second side members extending along the vehicle length and coupled with the first cross members and the second rear cross member. The first side members and the second side members are disposed such that their edge lines are connected along the vehicle length.