A sheet processing apparatus includes a first intermediate stacking portion which stacks a conveyed sheet and which performs process to the sheet, a stapler which performs process to the sheet on the first intermediate stacking portion, a second intermediate stacking portion which is located on an upstream side in a conveying direction of the stapler and which is capable of temporarily storing the conveyed sheet, and an intermediate roller pair which conveys the sheet on the second intermediate stacking portion to the first intermediate stacking portion. The sheet stacked on the first intermediate stacking portion and the sheet temporarily stored in the second intermediate stacking portion overlap each other.