Abstract: A packaging container made of flexible material has bottom and head ends along with front and rear walls. The front and rear walls have lower side borders juxtaposed to the bottom end and which are joined together along juncture fold lines which are parallel to one another. The front and rear walls have upper side borders juxtaposed to the juncture fold lines. The upper side borders of the front and rear walls are connected by side panels having outer fold lines at the second side borders and an inner fold line such that when the container is in a flat unfilled state, the side panels are sandwiched between the front and rear walls and the outer fold lines and inner fold lines respectively converge toward one another as the head end is approached.