An image forming element includes an image drum including a plurality of ring electrodes and a slot. The plurality of ring electrodes are formed to be spaced apart from one another on a circumference of the image drum. The slot is formed in a longitudinal direction on the image drum. A connecting member includes a plurality of connecting electrodes and is disposed inside the image drum so that an end of the connecting member is received in the slot. The connecting electrodes are electrically connected with the ring electrodes one to one on the same line.