In a case where components such as side flaps and crotch portions are arranged on multiple webs which are being conveyed while being arranged side by side in the width direction of the webs, articles in various sizes can be handled easily by a web conveying step of conveying a front waistline web 11A and a back waistline web 11B, the webs being arranged side by side in a width direction of the webs, a flap attaching step of attaching side flaps 30 onto the web 11 of the front waistline web 11A or the back waistline web, a web gap changing step of changing a gap between the front waistline web 11A and the back waistline web 11B by a web gap changing mechanism 500 and a crotch member attaching step of attaching a crotch member 20 between the front waistline web 11A and the back waistline web 11B, wherein the web gap changing step is performed between the flap attaching step and the crotch member attaching step.
