An image sensor and an image sensing method are provided. The image sensor includes a photodiode, a first storage circuit, a first readout circuit, a second storage circuit, and a second readout circuit. When the image sensor is operated in a dynamic vision sensing mode, the first storage circuit stores a first dynamic vision sensing signal provided by the photodiode during a first exposure period of a first frame period, and the second storage circuit stores a second dynamic vision sensing signal provided by the photodiode during a second exposure period of the first frame period. The first readout circuit and the second readout circuit output a first readout signal and a second readout signal to a first input terminal and a second input terminal of a differential amplifier at the same time according to the first dynamic vision sensing signal and the second dynamic vision sensing signal.