There are provided a sheet post-processing apparatus which can reliably stack a sheet bundle in imbricated state without bending it and an image forming apparatus having the same.A sheet post-processing apparatus includes: a stacking portion which stacks a folded sheet bundle subjected to the folding process; a discharge portion which discharges the folded sheet bundle onto the stacking portion with the folded end thereof set to the leading position; and a conveying portion which conveys the folded sheet bundle stacked onto the stacking portion, wherein the conveying portion starts the conveyance of a previous folded sheet bundle at the timing at which the folded end of a next folded sheet bundle discharged by the discharge portion is abutted onto the previous folded sheet bundle which is being conveyed to the downstream side in the discharge direction.