Disclosed is an active pixel sensor array, which can reduce the number of elements and the size of capacitors by enabling a reset switching transistor to include a function of an optical sensor and to reset a pixel voltage with a power supply voltage VDD after a gate selection signal is outputted, and to reset a pixel voltage with a power supply voltage VDD by a coupling function in case that a gate selection signal is outputted. The active pixel image sensor having a gate driving circuit and a column driving circuit includes a pixel composed of a voltage supply unit for supplying a signal voltage to the column driving circuit; a gate selection unit for turning on according to a n+1-th gate selection signal and outputting a voltage based on a difference between a pixel voltage and a threshold voltage of the voltage supply unit; a reset switching unit for turning on according to a n+1-th gate selection signal and resetting the pixel voltage with a power supply voltage VDD; and a storage unit and a coupling unit for coupling so as to initialize the pixel voltage to be lower than the power supply voltage VDD just after the n+1-th gate selection signal is outputted.