To prevent the deformation of a claw part by forming the claw part using the resin whose melting point is higher than that of the resin forming a bottom part to prevent the claw part from being melted off at the temperature when fitted to a bag body.

Both a male claw side chuck tape 1a and a female claw side chuck tape 1b are formed so as to be split into a bottom part 2 and a claw part 3, and the bottom part 2 is formed of the resin whose melting point is lower than that of the resin to form the claw part 3. The male claw side chuck tape 1a and the female claw side chuck tape 1b are inserted in the engaged condition inside a film 4 forming a bag body, and a Teflon-executed plate to prevent the fusion is inserted therebetween. A hot plate 6 is pressed from the film side to thermally fuse the bottom part 2 of the chuck tapes 1a, 1b to the film 4. Because the claw part 3 is not deformed near the melting point of the bottom part 2, and generation of defective engagement of the chucks can be suppressed low even when the production speed is increased.