Disclosed is an image sensor, which is characterized by increased strength of adhesion between a photoconductive layer and a front electrode made of aluminum, and which includes a first electrode composed of aluminum, copper or an aluminum-copper alloy on a substrate, a buffer layer formed on the first electrode, a photoconductive layer formed on the buffer layer, and a second electrode formed on the photoconductive layer, wherein the buffer layer includes a material having higher strength of adhesion than the photoconductive layer to the first electrode.