Abstract: A belt-shaped base of a female member of a zipper tape attached to an inner surface of a bag body has a wide portion that extends wider toward an opening of the bag body than a belt-shaped base of the male member. An open tape is disposed on the wide portion and a seal layer is laminated on a surface of the open tape. A first projecting portion is also provided on the wide portion. A second projecting portion is provided on an opening-side end of the belt-shaped base. The projecting portions have a substantially trapezoidal cross section. When the zipper tape is bonded to the bag body and is sealed by the seal layer, a gap is provided between the open tape and the first and the second projecting portions.