An image sensor includes an optical sensor layer including a plurality of light-sensitive cells configured to sense light to generate electrical signals, and a color filter array layer disposed on the optical sensor layer and including a plurality of color filters respectively facing the plurality of light-sensitive cells. Each of the plurality of color filters includes a nanostructure in which a first material having a first refractive index and a second material having a second refractive index higher than the first refractive index are arranged. The first material and the second material are alternatively positioned at an interval less than a central wavelength of a color of the color filter. Thus, a thin image sensor having good wavelength selectivity and suitable for obtaining high resolution images is provided.