To provide a finishing device for realizing tight packaging when both ends of a substantially rectangular film overlap in an envelope shape or a palm-folding shape, and heat-sealed in a cylinder, and an opening surface is heat-sealed.

A packaging machine heat-seals a substantially rectangular article (20) by a substantially rectangular film (10). Both ends of the substantially rectangular film (10) overlap and are heat-sealed in a cylinder, and a pair of films (11 and 12) facing an opening surface are pushed and expanded in the transverse direction along the center line. Another facing pair of films (13 and 14) overlap so that the film (10) is brought into contact with the article (20) by folding plates (21 and 21) from upper and lower parts, and pressed diagonally by seal plates (22 and 22) and heat-sealed.