A packaging and filling device for forming a paper container including a cylindrical body having four sidewalls and a substantially square cross section, a top and a bottom, the paper container being formed of a blank prepared by cutting a band-shaped packaging material made at least of an outermost thermoplastic layer, a paper layer and an innermost thermoplastic layer; the blank having a developed shape of the paper container and fold lines; the blank including a first bottom panel (1 b) and a third bottom panel extended the respective lower sides of a first panel and a third panel which are one pair of 2 container sidewalls opposed to each other; and a second bottom panel and a fourth bottom panel extended from the respective lower sides of a second panel and a fourth panel which are the other pair of 2 container sidewalls opposed to each other; the third bottom panel having a sixth panel partially extended from the center of the lower side of the third bottom panel; the sixth panel having a width which is 15 - 65% of a total length of the lower side of the third bottom panel, and a length necessary to delay the permeation leakage from the side surface; the blank including a plurality of top panels corresponding to the top of the paper container; the bottom of the paper container being formed by extending the sixth panel from the lower side of the third bottom panel; bending the second bottom panel and the fourth panel into triangular flaps with the lower side surfaces of the second and the fourth bottom panels faced outward and bending the flaps inward; laying the first bottom panel and the third bottom panel on the outsides of the second bottom panel and the fourth bottom panel with the first bottom panel positioned outside of the third bottom panel, and pressing from the inside and the outside, and heat-sealing, the device comprising: a loading means of taking out one out of a bundle of a plurality of blanks having vertically sealed and flattened; a bottom forming means of forming a bottom of the cylindrical blank to form the paper container having a top opening and a bottom; a filling means of filling liquid food through the top opening; and a top sealing means of heat-sealing the top opening; wherein, the loading means further includes a taking-out means which takes out the blank; an erecting means of erecting the flattened blank into the cylindrical blank; and an infeeder which inserts a mandrel of the bottom forming means into the cylindrical blank, a press station of the bottom forming means which presses the container bottom from the outside and the inside by the forward side surface of the mandrel and a press surface characterised in that the forward side surface of the mandrel has a triangular emboss at a position opposed to the position where the third bottom panel is exposed on the inside surface of the container, and in that the press surface includes a projected surface for forming a wide upward trench in the container bottom. a loading means of taking out one out of a bundle of a plurality of blanks having vertically sealed and flattened; a bottom forming means of forming a bottom of the cylindrical blank to form the paper container having a top opening and a bottom; a filling means of filling liquid food through the top opening; and a top sealing means of heat-sealing the top opening; wherein, the loading means further includes a taking-out means which takes out the blank; an erecting means of erecting the flattened blank into the cylindrical blank; and an infeeder which inserts a mandrel of the bottom forming means into the cylindrical blank, a press station of the bottom forming means which presses the container bottom from the outside and the inside by the forward side surface of the mandrel and a press surface characterised in that the forward side surface of the mandrel has a triangular emboss at a position opposed to the position where the third bottom panel is exposed on the inside surface of the container, and in that the press surface includes a projected surface for forming a wide upward trench in the container bottom.