NOVELTY - The welding method inserting an inner surface of the sealing segments (3,4) which has a groove-shaped dent (32,42) in welding surfaces (31,41) of a cylindrical film (2) and are positioned in the welding portion of the cylindrical film. The welding surfaces are provided a welding property. The cylindrical film is pressed against a dent from the outer side by the sealing segment of a protruding line corresponding to the groove-shaped dent. The cylindrical film is extended in the dent, and is welded to the sealing segment in an airtight manner.    USE - Welding method of sealing segment used for container (claimed) such as exterior container of secondary battery such as lithium ion battery and nickel-hydrogen battery, as well as used for packing material of foodstuffs such as liquid, viscous segment, powder, and granule, or heavy chemicals.    ADVANTAGE - The welding techniques of sealing segment are provided with simple manufacturing techniques, high productivity and a high freedom degree of the sealing segment to be used, without generating wrinkles. Since the side wall outer surface and cylindrical film of a sealing segment can be welded according to the container, even when a sealing segment is thinly lightweight, the wide welding surface is acquired. Thus the welding intensity is improved and the moisture-content invasion from a weld portion, and moisture-content dissipation of the content goods can be suppressed. Since it becomes a container of cylindrical shape, the rigidity of a container is improved. Since wrinkles do not enter into the cylindrical film of the sealing segment vicinity, the external appearance is enhanced. Since the sealing segment is cyclic, another segment which has various functions, such as a filling port and a pouring opening, can be provided in this sealing segment by a fitting or screwing. Thus a container is made applicable to various uses.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for container.    DESCRIPTION OF DRAWING(S) - The drawing shows the perspective view of the container with sealing segment.    Cylindrical film (2)    Upper sealing segment (3)    Lower sealing segment (4)    Upper welding surface (31)    Upper groove-shaped dent (32)    Lower welding surface (41)    Lower groove-shaped dent (42)