Abstract: A self-standing bag is made of two similar side wall sheets disposed in an opposing relation and a bottom wall sheet having two edges thereof heat-fused with the lower edges of the two side wall sheets and being folded along a central folding line into the interspace between the two side wall sheets to have an inverted V-shaped cross section, each of the two lateral edges of the bottom wall wheet being recessed from the lateral edges of the side wall sheets, whereby two lateral edges of the two side wall sheets are mutually joined directly, when subjected to heat-fusing operation, to form two-ply lap joints. The invention also provides method and apparatus for automatically producing the bag. SPThis application is a Divisional of Ser. No. 601,506 filed Aug. 4, 1975, now U.S. Pat. No. 3,980,225.

Abstract: A self-standing bag is made of two similar side wall sheets disposed in an opposng relation and a bottom wall sheet having two edges thereof heat-fused with the lower edges of the two side wall sheets and being folded along a central folding line into the interspace between the two side wall sheets to have an inverted V-shaped cross section, each of the two lateral edges of the bottom wall sheet being recessed from the lateral edges of the side wall sheets, whereby two lateral edges of the two side wall sheets are mutually joined directly, when subjected to heat-fusing operation, to form two-ply lap joints. The invention also provides method and apparatus for automatically producing the bag.