Disclosed is a WDR pixel array having high sensitivity under the middle intensity of illumination and high intensity of illumination by using the 4T pixel structure representing high sensitivity under the low intensity of illumination. According to the embodiment, the overflow charges generated under the very high intensity of illumination are not discarded or partially stored, but read through the 3T pixel operation, so that the WDR pixel array having high sensitivity under the middle intensity of illumination and high intensity of illumination can be obtained based on the 4T pixel structure without additionally providing a transistor or a photodiode for the high intensity of illumination in the WDR pixel array.