An image sensor includes a substrate including a pixel region and a pad region and having a first surface and a second surface opposite to the first surface, the pad region of the substrate being provided with a first recess which is recessed to a first depth from the second surface toward the first surface and the pixel region of the substrate being provided with a plurality of unit pixels, an interlayer insulating layer disposed on the first surface, an interconnection line disposed in the interlayer insulating layer, a conductive pad disposed in the first recess of the pad region, and a plurality of penetration structures disposed in the pad region of the substrate and extending from a bottom surface of the first recess to the first surface of the substrate, and electrically connecting the conductive pad to the interconnection line.