To increase number of categories of folding processes without increasing number of folding processing sections, the folding process being performed in an apparatus having the folding processing section for applying the folding process to a paper sheet.

A paper sheet is transported until a leading edge of the paper sheet abuts to a first end guide 62, and the paper sheet is further transported even after the leading edge of the sheet abuts to the end guide 62. This causes the paper sheet to be buckled at a center portion of the paper sheet as shown in Fig.10 (a). Then, the paper sheet is fed into a first folding roll 63 with the portion where the buckling has occurred heading first, and the first-time folding process is performed, as shown in Fig.10 (b). Thereafter, a paper sheet guide part 100 is protruded on an intermediate detour transport path 52b until the leading edge of the paper sheet reaches the paper sheet guide part 100. By so doing, the paper sheet is moved toward a second folding roll 65, as shown in Fig.10 (c).