Provided is an image sensor, which includes: a first substrate; a first structure on a front surface of the first substrate, the first structure including a first interlayer insulating layer surrounding a first conductive layer; a second substrate; a second structure on a front surface of the second substrate facing the front surface of the first substrate, the second structure including a second interlayer insulating layer, the second interlayer insulating layer being bonded to the first interlayer insulating layer; an organic photoelectric layer on a back surface of the second substrate; and a via electrode structure in contact with the first conductive layer through the second substrate and the second structure, the via electrode structure including an air gap therein.