A Time-of-Flight (ToF)-based three-dimensional (3D) image sensor includes at least two first photogates symmetrically arranged in a central portion of a pixel, at least two first gates configured to remove an overflow charge generated in the at least two first photogates, and a first gate group. The at least two first gates are arranged symmetrically in an outer portion of the pixel. The first gate group includes a plurality of gates configured to store and transmit charges generated in the at least two first photogates. The first gate group is arranged in the outer portion of the pixel.