Sheet processing apparatus and image forming system

摘要

A sheet processing apparatus (100) includes: a first conveying member pair (2; R3, R4) that folds a sheet; a second conveying member pair (3, R6; R6a, R6b) that conveys downstream the sheet folded by the first conveying member pair (2; R3, R4); and a third conveying member pair (4; R3, R5) that further folds the sheet folded by the first conveying member pair (2; R3, R4). The second conveying member pair (3, R6; R6a, R6b) is rotatable forward and reversely when driven to convey, and is locked in one rotational direction but is rotatable in the other rotational direction when not driven.