An electrophotographic image forming apparatus is usable with a process cartridge having a photosensitive member. The apparatus includes a transfer member contactable to the photosensitive member to transfer a toner image from the photosensitive member thereonto, a tray carrying the cartridge and movable between a contact position where the photosensitive member contacts the transfer member and a spaced position spaced from the transfer member, a supporting member supporting the tray for movement parallel with a tangent line between the photosensitive member and the transfer member between a first position positioning the tray at the contact position and a second position retracted from the first position away from the transfer member in a perpendicular direction perpendicular to the photosensitive-member axial direction and to the tangent line to position the tray at the spaced position; and engageable and engaging portions engageable with each other. The engaging portion regulates movement of the tray.