An image forming apparatus comprising: an image forming portion configured to form an image on a sheet; an oblique movement correcting portion provided upstream of said image forming portion with respect to a sheet feeding direction and including a first registration roller pair for correcting oblique movement of the sheet by abutting a leading end of the sheet against said first registration roller pair and first moving means for moving the sheet in a widthwise direction of the sheet perpendicular to the sheet feeding direction in a state in which the sheet is nipped in said first registration roller pair; a reversing portion configured to reverse the leading end and a trailing end of the sheet on which the image is formed on a first surface by said image forming portion; and a re-feeding portion configured to re-feed the sheet reversed by said reversing portion toward said oblique movement correcting portion, wherein said reversing portion includes a reversing roller pair (132a, 132b) for reversing the sheet by rotating in a first direction while nipping the sheet and then by rotating in a second direction opposite to the first direction, and includes second moving means for moving the sheet in the widthwise direction in a state in which the sheet is nipped by said reversing roller pair (132a, 132b), wherein said re-feeding portion includes a second registration roller pair for correcting the oblique movement of the sheet by abutting a leading end of the sheet reversed by said reversing portion against said second registration roller pair, and wherein when an image is formed on a second surface of the sheet opposite from the first surface of the sheet, a side end position of the sheet is corrected by said second moving means and the oblique movement of the sheet is corrected, and then the side end position of the sheet is corrected again by said first moving means and the sheet is fed to said image forming portion. an image forming portion configured to form an image on a sheet; an oblique movement correcting portion provided upstream of said image forming portion with respect to a sheet feeding direction and including a first registration roller pair for correcting oblique movement of the sheet by abutting a leading end of the sheet against said first registration roller pair and first moving means for moving the sheet in a widthwise direction of the sheet perpendicular to the sheet feeding direction in a state in which the sheet is nipped in said first registration roller pair; a reversing portion configured to reverse the leading end and a trailing end of the sheet on which the image is formed on a first surface by said image forming portion; and a re-feeding portion configured to re-feed the sheet reversed by said reversing portion toward said oblique movement correcting portion, wherein said reversing portion includes a reversing roller pair (132a, 132b) for reversing the sheet by rotating in a first direction while nipping the sheet and then by rotating in a second direction opposite to the first direction, and includes second moving means for moving the sheet in the widthwise direction in a state in which the sheet is nipped by said reversing roller pair (132a, 132b), wherein said re-feeding portion includes a second registration roller pair for correcting the oblique movement of the sheet by abutting a leading end of the sheet reversed by said reversing portion against said second registration roller pair, and wherein when an image is formed on a second surface of the sheet opposite from the first surface of the sheet, a side end position of the sheet is corrected by said second moving means and the oblique movement of the sheet is corrected, and then the side end position of the sheet is corrected again by said first moving means and the sheet is fed to said image forming portion.