To provide a package film seal device capable of positioning a message on a cover film to a container film, and stabilizing adhesive strength between the cover film and the container film to secure sealing performance of a container.

A package film seal device to seal a cover film 15 having a message printed on the surface to a container film 12 in which a pocket 12a is molded to manufacture a package film comprises a container film holding roller 11 to hold the container film 12, a heating roller to heat the cover film 15 to be affixed to the container film 12, a preheating roller 16 which is located on an upper stream side of the heating roller 13 to carry the cover film 15 synchronously with the heating roller 13, and preheat the cover film 15, a sensor 21 to detect the message on the cover film 15, and a second carrying roller 20 which is located on an upper stream side of the preheating roller 16 to position the cover film 15 to the container film 12 in accordance with the position of the cover film 15 detected by the sensor 21.