An image sensor includes an upper chip having a pixel array connected to a first connecting structure, and a lower chip below the upper chip and having a second connecting structure connected to the first connecting structure and having first and second stacked metal layers with a same thickness, a third metal layer on the second metal layer and thicker than the second metal layer, a fourth metal layer on the third metal layer and thicker than the third metal layer, first through third insulating layers alternating with the first through fourth metal layers, a first memory device with a first MTJ element in at least one of the first and second insulating layers, and a second memory device with a second MTJ element different from the first MTJ element, the second MTJ element being in at least one of the first through third insulating layers.