An image sensor includes a substrate that includes a pixel regions; an insulating structure on the substrate; a grid pattern structure on the insulating structure; color filters on the insulating structure; and microlenses on the color filters. The grid pattern structure includes a first pattern portion and second pattern portions. The first pattern portion includes a first material pattern on the insulating structure, and a second material pattern on the first material pattern. The first material pattern is formed of a first material, and the second material pattern and the second pattern portions are formed of a second material. The first pattern portion includes parallel first horizontal straight portions, and parallel first vertical straight portions, and each of the second pattern portions includes a second horizontal straight portion parallel to the first horizontal straight portions and a second vertical straight portion parallel to the first vertical straight portions.