An image forming apparatus of the present invention includes a photoreceptor drum on which a toner image is formed, a transfer drum for transferring the toner image to paper by bringing the paper into contact with the photoreceptor drum, the transfer drum having a dielectric layer, a semi-conductive layer and a conductive layer laminated in this order from the paper side, a power source which is connected to the conductive layer so as to apply a predetermined voltage to the conductive layer, and a conductive roller for pressing the paper against a surface of the dielectric layer so as to produce a potential difference between the conductive layer and the paper. The potential difference induces charges of the same polarity as the voltage applied to the conductive layer on the surface of the dielectric layer, and charges of the opposite polarity on a back surface of the paper pressed against the surface of the dielectric layer. Thus, the paper electrostatically adheres to the transfer drum in a satisfactory manner. Moreover, unlike charging by atmospheric discharge, since the surface potential of the transfer drum is stable, it is possible to prevent unsatisfactory transfers and improve the image quality.