A sheet post-processing apparatus includes a discharge portion configured to discharge a sheet having a folding portion, a conveyance portion configured to abut on a lower surface of the sheet discharged by the discharge portion, to convey the sheet downstream in a sheet conveyance direction of the discharge portion, a pressing portion arranged at a position opposing the conveyance portion, configured to press an upper surface of the sheet discharged by the discharge portion, and a moving portion configured to move the pressing portion in the sheet conveyance direction of the conveyance portion, in which the moving portion moves the pressing portion upstream in the sheet conveyance direction of the conveyance portion, to move the pressing portion from a position where the sheet discharged by the discharge portion is not pressed to a position where the sheet discharged by the discharge portion is pressed.