PURPOSE: To provide a manufacturing method which can surely manufacture realistically and refinedly a mascot shaped balloon which is even in a complicated shape such as various kinds of animals, an airplane, an airship or the like.
CONSTITUTION: A composite film where a thermal fusion bonding layer 3 is formed on one suface of a resinous base film 1 is prepared, two of these composite films 4 and 5 are piled up in such a way that the respective thermal fusion bonding layers are faced to each other. The other composite film 6 for forming the specified portion of a bslloon is folded so as to be interposed at one portion between these two composite films 4 and 5 in such a way that its outer surface is faced to the thermal fusion bonding layers, and the respective composite films are then fusion bonded so as to be formed into a specified outer shape of a balloon in such a way that a part of the other composite film 6 is caught by the aforesaid outer shape thereafter.