The present invention provides a sheet feeding apparatus comprising a sheet stacking means for supporting a sheet, a sheet feeding means for feeding out the sheet supported by the sheet stacking means, a pair of side guides having sheet abutting surfaces for regulating both lateral edges of the sheet supported by the sheet stacking means to guide the sheet in a sheet feeding direction when the sheet is fed out from the sheet stacking means by the sheet feeding means, and a guide supporting means for supporting at least one of the pair of side guides for movement toward and away from the other side guide, and wherein the guide supporting means supports the side guide in such a manner that the sheet abutting surface is inclined with respect to the sheet feeding direction in accordance with a size of the sheet supported by the sheet stacking means.