A paper transport mechanism is used in an image forming apparatus in which a toner image formed on a surface of a photosensitive member is transferred by an image transfer voltage generated by an image transfer unit onto paper which has been fed from a paper storage up to the photosensitive member through a paper path. The paper transport mechanism is provided with a first roller having a width not smaller than a maximum width of the paper stored in the paper storage, a group of second rollers aligned along the first roller for gripping the paper therebetween and transporting it toward the photosensitive member, each of the second rollers having a small width, and a non-undulation guide member provided immediately upstream of the first and second rollers for pressing the paper passing through the paper path against the first roller, the non-undulation guide member having a width not smaller than the maximum paper width. The paper fed from the paper storage is pressed against the first roller across the full paper width before the first and second rollers grip the paper. The paper is transported toward the photosensitive member without taking a wavy form so that the whole area of the paper comes into close contact with the photosensitive member. This helps prevent print image dropouts which may otherwise occur in a toner image transfer process.