An image forming apparatus has a pair of registration rollers which are moved in the width direction so that a sheet side end position is within a predetermined range in the width direction based on sheet side end position information from a lateral registration detection sensor. In the case that an image-formed sheet is conveyed to a sheet processing portion without being reversed, the pair of registration rollers are moved so that the sheet side end position is within the first range, and in the case that an image-formed sheet is conveyed to the sheet processing portion, the pair of registration rollers are moved so that the sheet side end position is within the second range being different from the first range before reversing and within the first range after reversing.