To solve a problem in the prior art wherein a strip tape is elongated and broken around both edge portions in splicing since the tensile stiffness of the splice tape is too much decreased by heat to hold the slice portion and therefore it is necessary to stop the filling machine to reset the strip tape from the beginning.

A filling machine making a packaging material into cylindrical shape and continuously forming containers laps the edge portion of the present strip tape on the edge portion of the next strip tape and heat-seals them such that the heat pattern is substantially discontinuous at least in both edge portions of the strip tape in the splice portion whereby the splice of the strip tape can keep enough tensile stiffness without being influenced by heat.