In an image forming apparatus such as a color laser printer wherein a toner image is transferred onto a continuous paper, one or more of a exposure timing of each exposure device, a rotation speed of each image carrier device, a transfer bias voltage applied to each transfer device, and a wrap amount of each wrap device are controlled based on a coverage of a toner image formed on each image carrier device, thereby preventing a color-to-color registration state which tends to be caused due to a variation in the transport speed of the continuous paper in a transfer process.