The skew feeding amount of a sheet front end is calculated according to the difference between timings when activation sensors detect the sheet front end, and the skew feeding amount of the sheet side edge is calculated according to the difference between side edge positions of the sheet detected by the first side registration detection sensor or the second side registration detection sensor. Further, whether a sheet is a rectangular sheet or a non-rectangular sheet is determined before skew feeding of the sheet is corrected, and, when the sheet is determined to be a rectangular sheet, the skew feeding correcting portion is controlled based on one of the sheet side edge skew feeding amount and sheet front end skew feeding amount and the skew feeding correcting portion is controlled based on the sheet side edge skew feeding amount when the sheet is determined to be a non-rectangular sheet.