PROBLEM TO BE SOLVED: To prevent distortion generated on a diaper continuous body when fitting a post-treatment tape.SOLUTION: A conveyance step causes first conveyance means 21 and a second conveyance means 22 to convey a diaper continuous body 10, with a direction matching the width direction defined as a conveyance direction, the second conveyance means 22 being disposed at some interval part from the first conveyance means 21 in the conveyance direction. A tape fitting step causes tape fitting means 23 provided between the first conveyance means 21 and the second conveyance means 22 to fit a post-treatment tape 5 to an outer surface of a front body 1 or a back body 2 of the diaper continuous body 10 during the conveyance step. A press conveyance step causes press conveyance means 24 provided between the first conveyance means 21 and the second conveyance means 22 to convey the diaper continuous body, with a part or the whole body of a crotch part 3 of the diaper continuous body 10 clamped between both surfaces of a surface in the front body 1 side and a surface of the back body 2 side when executing the tape fitting step.
