A self-standing bag (1) comprising a bag body (2), a spout (3), and a reverse-recessed frame (4), wherein the spout (3) is provided at the upper portion of the bag body (2) composed of body films (2c, 2c) and a bottom film (2d) folded down on the bottom portion in a reverse V-shape, and integrally formed with the reverse-recessed frame (4) starting at the upper edge (2b) toward both side edges (2a, 2a) of the bag body (2), the bag body has fusion bonding parts at the lower edges and a part of each side edge of the bag body (2) which are fusion bonded to each other so that at least the bottom film (2d) can be fixed to the body films (2c, 2c).