A sheet post-processing apparatus (1) includes a first stapler (4) and a
second stapler (5) for stapling the stack of sheets on a stack tray (61),
a first moving frame member (10) on which the first stapler (4) is
mounted rotatably, a second moving frame member (11) on which the second
stapler (5) is mounted, a rotating member (20) rotatably mounted on the
first moving frame member (10), the rotating member (20) so held in
engagement with the first moving frame member (10) as to move linearly
the first moving frame member (10) by rotation of the rotating member
(20), and also rotating the first stapler (4) by rotation of the rotating
member (20), and a single drive power source (16) for driving the
rotating member (20).