Provided is a unit pixel which uses three transistors and a pixel array including the unit pixel. The unit pixel includes a photodiode, a charge passing unit, a reset controller, and a voltage converter. The pixel array has a structure in which a plurality of the unit pixels according to the present invention are two-dimensionally arrayed, and includes one or more reset power supply circuits which output two or more different supply voltages in response to a pixel selection control signal. Parts of a plurality of the unit pixels share a voltage output from the reset power supply circuit.