An image sensor includes a substrate having first and second surfaces, pixel regions arranged in a direction parallel to the first surface, first and second photodiodes isolated from each other in each of the pixel regions, a first device isolation film between the pixel regions, a pair of second device isolation films between the first and second photodiodes and extending from the first device isolation film, a doped layer adjacent to the pair of second device isolation films and extending from the second surface to a predetermined depth and spaced apart from the first surface, the doped layer being isolated from the first device isolation film, and a barrier area between the pair of second device isolation films and having a potential greater than a potential of a portion of the substrate adjacent to the barrier area.