A sheet post-processing device includes: a loading assist mechanism including a flapping member, a pressing member, a first power transmission mechanism that pivots the flapping member from a first ready-to-pivot position, a second power transmission mechanism that pivots the pressing member from a second ready-to-pivot position, a rotary member that transmits, during rotation in a first direction, power to the first power transmission mechanism, and transmits, during rotation in a second direction, power to the second power transmission mechanism, and a drive source that rotates the rotary member; and a control device that controls the drive source to control an angle of rotation of the rotary member in the first direction, thus controlling an angle of pivoting of the flapping member, and controls the drive source to control an angle of rotation of the rotary member in the second direction, thus controlling an angle of pivoting of the pressing member.

A sheet post-processing device includes: a loading assist mechanism including a flapping member, a pressing member, a first power transmission mechanism that pivots the flapping member from a first ready-to-pivot position, a second power transmission mechanism that pivots the pressing member from a second ready-to-pivot position, a rotary member that transmits, during rotation in a first direction, power to the first power transmission mechanism, and transmits, during rotation in a second direction, power to the second power transmission mechanism, and a drive source that rotates the rotary member; and a control device that controls the drive source to control an angle of rotation of the rotary member in the first direction, thus controlling an angle of pivoting of the flapping member, and controls the drive source to control an angle of rotation of the rotary member in the second direction, thus controlling an angle of pivoting of the pressing member.