To provide a method for welding a sealing member to a cylindrical film of a high degree of freedom in the using sealing member with the simple manufacturing equipment, and a container that is small in risk of moisture intrusion from a welding part of a cylindrical film and a sealing member and dissipation of liquid component from contents, is light and compact, is high in mechanical strength, is high in the degree of freedom in using the sealing member with the simple manufacturing equipment and is high in the productivity.

A cylindrical film 2 having at least an inner surface of a welding property is air-tightly welded with the sealing members 3 and 4 by: inserting the sealing members 3 and 4 having groove shape dents 32 and 42 that accommodate a part of the cylindrical film 2 at the welding surface 31 and 41 and arranging them at a welding location of a cylindrical film 2; pressing the cylindrical film 2 against the dents 32 and 42 with protrusion-sealing members corresponding to the grooved dents 32 and 42 from the outside cylindrical film 2; and extending the cylindrical film 2 at the dents 32 and 42.