An image forming apparatus includes an image bearing member for bearing an image, a transfer charging device for transferring the image from the image bearing member onto a recording material at a transfer position, a power source for supplying a voltage to the transfer charging device during an image transfer operation, and a control device for changing an output of the transfer charging device from a first level to a second level prior to arrival of an image area of the image bearing member at the transfer position, wherein the second level is higher than a third level of the output which is a level when the image area is at the transfer position.