The present invention provides a new bag-making machine with a special configuration, making it so that a protruding section is formed on one end face of a plastic bag without separately supplying bottom gusset material. Near one side edge (21) of a first body material (1), the first body material (1) is folded along a first folding line (5) and near the corresponding side edge (22) of a second body material (2), the second body material (2) is folded along a second folding line (6) to form a first folded section (23) in the first body material (1). When folded, the distance between the one side edge (21) and the first folding line (5) is greater than twice the distance between the corresponding side edge (22) and the second folding line (6) by a set distance (L3). Consequently, one end face is formed by the first folded section (23) and the protruding section is formed by the set distance (L3).