Image sensors include a first insulation interlayer structure on a first surface of a substrate and having a multi-layered structure. A first wiring structure is in the first insulation interlayer structure. A via contact plug extends from a second surface of the substrate and penetrates the substrate to be electrically connected to the first wiring structure. Color filters and micro lenses are stacked on the second surface in a first region of the substrate. A second insulation interlayer structure is on the second surface in a second region of the substrate. A second wiring structure is in the second insulation interlayer structure to be electrically connected to the via contact plug. A pad pattern is electrically connected to the second wiring structure and having an upper surface through which an external electrical signal is applied. Photodiodes are between the first and second wiring structures in the first region.