To heighten the separating action of overlapping pages and further heighten the page-turning accuracy.

After the execution of the swollening treatment of the pages of a pamphlet at the steps (S3 to S5), a next page falling off treatment is executed at the step (S6). This treatment is executed by turning a turning-over roller to a direction opposite to a page-turning direction under the condition that the pamphlet is urged against the turning-over roller with a pamphlet pressing member under an urging force weaker than the force applied during the execution of the page swollening treatment at the steps (S3 to S5). Thus, even under the state that the pages following the next page swollen a little due to the friction with the uppermost swollen page, the pages following the next page can be effectively fallen off the swollen uppermost page so as to allow to spring up the swollen uppermost page under the state, resulting in heightening the separating action of the overlapped pages and allowing to furthermore heighten the page-turning accuracy.