PROBLEM TO BE SOLVED: To prevent adhesive strength from being lowered in a heat sealing processing.SOLUTION: A heat sealing device includes a drum 2 and a rotary portion each which rotate centering around a center axis parallel to each other, and the drum and the rotary portion each have a sealing processed portion extending parallel to the center axis. A heat sealing processing is carried out by sandwiching a target site of a continuous sheet 9 between these sealing processed portions. A pair of contact portions 5 contacting the continuous sheet are provided in the vicinity of both sides of the sealing processed portion 23 in a circumferential direction centering around the center axis of the drum. Passing through a center between the pair of contact portions in the circumferential direction and considering a direction perpendicular to the center axis as a noted direction, a distance in the noted direction between the position of the continuous sheet in one of the contact portions and the center axis is longer than a distance in the noted direction between a processed surface 242 of the sealing processed portion and the center axis. As a result, lowered adhesive strength caused by overheating of the target site when processing is not performed is prevented.
