A transferring device in which a transfer roller having a diameter which is not less than 60% of the diameter of an organic photosensitive drum with a diameter of 10 to 20 mm is arranged with a clearance provided between the transfer roller and the organic photosensitive drum. The transferring device avoids problems such as current leakage and reverse transfer of toner in the case of miniaturization of an image forming apparatus or contamination of the transfer roller, and easily sets a transfer current because an effective transfer current width is large.