An image sensor may include a substrate having a first surface and a second surface, which are opposite to each other, and micro lenses on the second surface, interconnection lines on the first surface, and a pixel isolation portion in the substrate, the pixel isolation portion configured to isolate pixels from direct contact with each other. The pixel isolation portion may include an insulating isolation pattern and a conductive pattern, wherein the conductive pattern is spaced apart from the substrate, and the insulating isolation pattern is between the substrate and the conductive pattern. The conductive pattern may include a sequential arrangement of a first conductive pattern, a second conductive pattern, and a third conductive pattern on a side surface of the insulating isolation pattern.