To reduce waste of roll paper, in a roll paper mounting device for double-folding the roll paper and conveying the roll paper to a discharge port with the edge of the double-folded paper in the lead.

The mounting device comprises a main driving roller 21 for conveying the roll paper 6 toward the discharge port 7, a sub driving roller 28 for conveying the roll paper 6 in the return direction to a storing part 5b, and also a mechanism for moving a pressing roller 52 to one of a first position contacting with the main driving roller 21 and a second position contacting with the sub driving roller 28. Thus, the roll paper 6 can be returned to the storing part 5b side, and the double-fold part formed at the tip of the roll paper can be shortened before conveying the roll paper 6 to the discharge port 7.