An image forming apparatus includes an image bearing member for carrying a toner image; a transfer member for cooperating with the image bearing member to form a nip to transfer a toner image onto a transfer medium; transfer voltage applying means for applying a transfer voltage to the transfer member to transfer the toner image; detecting means for detecting a current when a monitor voltage is applied to the transfer member; transfer voltage determining means for determining the transfer voltage on the basis of a detection result of the detecting means so that current through the transfer member in a transfer operation is the target current; and target current adjusting means for adjusting the target current so that target current when a resistance of the transfer member is relatively small is larger than the target current when the resistance value of the transfer member is relatively large.