1. An image sensor, comprising: a semiconductor substrate; a logic circuit region, formed on the substrate, the logic circuit region including a plurality of gate patterns; an image-sensing element region formed in a region different from the logic circuit region on the substrate, a plurality of image-sensing elements being formed in the image-sensing element region and a plurality of dummy gate patterns formed with a constant pitch on the image-sensing element region; and dummy element isolation portions in the image-sensing element region.