A unit pixel of an image sensor includes a photoelectric conversion region, a floating diffusion region, and a transfer gate. The photoelectric conversion region is in an active region defined by an isolation region of a semiconductor substrate. The photoelectric conversion region generates electric charges corresponding to incident light. The transfer gate transfers the electric charges to the floating diffusion region, which is located in the active region. The transfer gate includes first and second portions divided relative to a reference line, and at least one of the first or second portions does not overlap the isolation region.