Patent ID: 8505900

Claim:
A sheet post-processing apparatus comprising: a holding unit that holds a booklet containing folded sheets; a pressing unit having a pressing surface that presses a spine of the booklet held by the holding unit in a pressing direction perpendicular to a thickness direction of the booklet to deform the spine into a square shape; a moving unit that moves the pressing unit forward and backward along the spine while the pressing surface of the pressing unit is pressing the spine; and a changing portion that changes a pressing position of the pressing surface at which the pressing surface presses the spine in the pressing direction, wherein the changing portion changes the pressing position so that, when squaring of the spine is performed while the pressing unit reciprocates along the spine of the booklet by the moving unit, a distance in the pressing direction between a top of the spine prior to pressing by the pressing surface and the pressing position is changed such that the distance during a backward movement of reciprocating the pressing unit becomes larger than the distance during a forward movement.