An image sensor may include a pixel array including a plurality of pixel blocks operable to convert light into electrical signals. Each of the plurality of pixel blocks may include a first light receiving circuit including a plurality of unit pixels that share a first floating diffusion; a second light receiving circuit arranged adjacent to the first light receiving circuit in a second direction, and including a plurality of unit pixels that share a second floating diffusion; a first driving circuit positioned between the first light receiving circuit and the second light receiving circuit; a second driving circuit positioned adjacent to the other side facing away from one side of the first light receiving circuit or the second light receiving circuit, which is adjacent to the first driving circuit; and a third driving circuit positioned adjacent to the first driving circuit or the second driving circuit.