To simply and inexpensively manufacture a continuous polyethylene bag wherein a large number of polyethylene bags having "handle parts" are continued in a strip-like form.

In the manufacturing method of the continuous polyethylene bag, first, both side parts in the width direction of a cylindrical plastic sheet 30 are inwardly folded into a valley form to form gussets 18. Succeedingly, the parts where the gussets 18 are formed are linearly thermally welded in the width direction thereof to form welded parts 22b which constitute the upper ends of the handle parts 22 and the cylindrical plastic sheet 30 is linearly thermally welded over the whole length in its width direction to form a bag bottom 20. Then, the parts where the gussets 18 of the cylindrical plastic sheet 30 are formed are folded to be superposed on the surface of the cylindrical plastic sheet 30 to arrange the valley bottom parts 18a of the gussets 18 on both side ends in the width direction of the cylindrical plastic sheet 30. Thereafter, the both side ends in the width direction of the cylindrical plastic sheet 30 are partially punched to form windows 22c on the valley bottom parts 18a of the gussets 18 to form annular handle parts 22.