To reduce the waste of paper roll in a paper roll mounting device wherein the paper of the paper roll is folded into two, and conveying the paper roll to an ejection port with a folded edge as the lead.

In this paper roll mounting method comprising an accommodating part 5b for accommodating the paper roll 6, an opening and closing cover 1 for covering the accommodating part 5b, and a paper pressing part 50 mounted on the cover 1 and folding the paper of the paper roll 6 pulled out from the accommodating part 5b, into two by closing the cover 1, and conveying the paper roll 6 to the ejection port 7 with the folded edge 6b of the paper roll 6 as the lead, a pulled-out part of the paper roll 6 is temporarily pulled back (ST4) after the cover 1 is closed (ST2), and the folded part 6b of the paper roll 6 as the lead is conveyed to the ejection port 7 (ST6), after the pulled-back part of the paper roll 6 is returned to a predetermined amount accommodating part 5b (ST3).