An image forming apparatus includes a first image-bearing member such as an electrophotographic photosensitive member, an intermediate transfer member for receiving a transferable image formed on the first image-bearing member, and contact transfer device for transferring the transferable image from the intermediate transfer member to a transfer material. The first image-bearing member has a surface layer having a dielectric constant .epsilon..sub.d, the intermediate transfer member has a surface layer having a dielectric constant .epsilon..sub.ITD and the contact transfer device has a surface layer having a dielectric constant .epsilon..sub.tr satisfying a relationship of; .epsilon..sub.d .ltoreq..epsilon..sub.ITD .ltoreq..epsilon..sub.tr. The intermediate transfer member exhibits a volume resistivity of 10.sup.6 -10.sup.10 ohm.cm (at an applied voltage of 1 kV), and the contact transfer device exhibits a volume resistivity of 10.sup.8 -10.sup.15 ohm.cm (at an applied voltage of 1 kV). As a result, it is possible to obtain high transfer efficiencies in both primary and secondary transfer over a wide transfer bias application range.