An image sensor includes a substrate including a photoelectric conversion part therein, and a fixed charge layer provided above the substrate. The fixed charge layer includes a first metal oxide and a second metal oxide, which are different from each other. The first metal oxide includes a first metal, and the second metal oxide includes a second metal different from the first metal. Concentration of the first metal in the fixed charge layer progressively increases from an upper portion of the fixed charge layer to a lower portion of the fixed charge layer.