An optical filter includes a substrate including a plurality of pixel areas spaced apart from each other and a light-blocking area between the plurality of pixel areas, a plurality of color filters arranged on a first surface of the substrate and corresponding to the plurality of pixel areas, and a plurality of conversion layers arranged on the first surface of the substrate and corresponding to the plurality of color filters. Each of the conversion layers includes inclined side surfaces. The optical filter further includes a reflective layer on the inclined side surfaces of each of the plurality of conversion layers. The reflective layer extends to the light-blocking area and is arranged consecutively on two adjacent inclined side surfaces from among the inclined side surfaces of the plurality of conversion layers and the light-blocking area between the two adjacent inclined side surfaces.