An image forming apparatus includes an image carrier for carrying developer image, a transfer device configured to transfer the developer image to a recording media, a forward bias applying circuit configured to apply a forward bias voltage to the transfer device, and a reverse bias applying circuit configured to apply a reverse bias voltage to the transfer device. The apparatus includes a detecting circuit configured to detect inflow current flowing from the image carrier into the forward bias applying circuit, and a decision circuit configured to determine a lower limit of the reverse bias voltage based on a detected value of the inflow current when the detected value of the inflow current exceeds a first predetermined value. The reverse bias applying circuit applies the reverse bias voltage of the determined lower limit to the transfer device at least before the forward bias voltage is applied to the transfer device.