An image forming apparatus includes a photosensitive drum; a charger; an intermediary transfer belt; a transfer member; a constant voltage element; a switch for selectively providing a first state using the constant voltage element and a second state not using the constant voltage element; a voltage source for applying a current to the constant voltage element by applying a voltage of a second polarity opposite the first polarity to the transfer member to form a secondary electric field in the secondary-transfer position and a primary electric field in the primary transfer position; and a controller for executing an adjustment applying the second polarity voltage to the transfer member when neither the primary-transfer operation nor the secondary-transfer is carried out, wherein the controller provides the second state using the switching portion in a period in which the second polarity voltage is applied to the transfer member.