To attach sheets or their equivalents to predetermined pages of main sheets subjected to continuous printing before folded in zigzag.

A sheet attachment device 60 is arranged between a lateral sewing device 30 and a separating device 40. Sheets 61 are fed from a sheet placement 62 to the main sheets 13 subjected to continuous printing, pasted in a spotted form with a pasting nozzle 71 and paste-attached to the sheet faces of the main sheets at their predetermined pages. Then, the main sheets are separated as a one-volume paged article by the separating device and folded in zigzag to the size of original sheets at the predetermined page in the flow direction by a zigzag folding device 50 to make a main sheet collated product.