A sheet processing apparatus includes a conveying portion which can move a sheet in a sheet conveying direction and in a sheet width direction, a moving portion which moves the conveying portion in the sheet width direction, a punching portion which punches a hole in the sheet, and a pressing portion which presses an upstream end of the sheet. The sheet forms a first loop to correct skew feeding while the sheet is conveyed with its downstream end abutted against the conveying portion in the sheet conveying direction. The conveying portion conveys the sheet. The moving portion moves the conveying portion in the sheet width direction to correct lateral registration of the sheet. The pressing portion presses an upstream end of the sheet in the sheet conveying direction and forms a second loop of the sheet to correct skew feeding. The sheet is positioned with reference to the pressing portion.