An image forming apparatus which can prevent the electric discharge when the trailing edge of a recording material passes a transferring position, and yet can stabilize the surface potential of a photosensitive drum. A controller changes a transfer bias voltage Vt during the supply of paper to 0 V before the trailing edge of recording paper arrives at a transferring nip part, changes it to a transfer bias voltage V₀ during the non-supply of paper after the trailing edge of the recording paper has passed the transferring nip part, and changes a charging bias voltage to a charging bias voltage smaller than a normal charging bias voltage when an area on the photosensitive drum to which 0 V has been applied passes a charging nip portion. The transfer bias voltage V₀ during the non-supply of paper is smaller than the transfer bias voltage Vt during the supply of paper.