To provide a folding/insertion device capable of accurately folding/inserting even thin paper or paper with less perforation.

In the folding/insertion device 2 for continuation paper 5, a folding/insertion mechanism 12 for forming a folding/insertion part along a conveying direction of the continuation paper 5. The folding/insertion mechanism 12 is constituted such that a first projection rod 121 projected toward a paper surface side of the continuation paper 5; a crest type roller 122 provided on a distal end of the first projection rod 121; and a receiving member 123 provided at an opposed position of the crest type roller 122 are provided. Further, a second projection rod 128 projected toward the paper surface side of the continuation paper 5 is provided on an oblique position opposed to the first projection rod 121 and a crest type roller 129 inclined with a rotation axis is provided on a distal end of the second projection rod 128.