A sheet post-processing apparatus of the present invention comprises: a sheet discharge section that feeds a sheet supplied from an image forming apparatus to a post-processing section and leads the sheet that has passed through the post-processing section to a sheet discharge port; a sheet discharge tray that receives a sheet discharged from the sheet discharge port and can move to a first standby position and a second standby position higher than the first standby position and nearer to the sheet discharge port; and a controller that controls the height position of the sheet discharge tray by identifying the type of the sheet. The controller changes the height position of the sheet discharge tray to allow the sheet discharge tray to receive the discharged sheet at the first standby position in the case where the sheet is a first type while to receive the discharged sheet at the second standby position in the case where the sheet is a second type.