To prevent the fusion with a separator, the fusion of chuck tapes to each other, or the blocking when the chuck tapes are attached to a base film by using, for forming an upper part of a bottom part, a resin whose melting point is higher than the melting point of the resin to form other parts.

A male side chuck tape 1a and a female side chuck tape 1b respectively comprises a bottom part 2, claw parts 3a, 3b, and a neck part 4. An upper part 21 located on each side part of the neck part 4 on an upper surface of the bottom part 2 using the resin whose melting point is higher than that of the resin to form other parts. In fitting the chuck tape to a bag body, a separator 7 is inserted between the upper part 21 of the male side chuck tape 1a and the upper part 21 of the female side chuck tape 1b, a hot plate 6 is pressed thereagainst from a base film 5 side to thermally fuse a back side of the bottom part 2 to the base film 5. Because the melting point of the resin to form the upper part 21 of the bottom part 2 is high, the fusion to the separator 7 can be prevented.