A method of resetting a time-based CMOS image sensor may be provided, where the time-based CMOS image sensor may include a photodiode, a transfer transistor transferring photo-generated charges generated in the photodiode to a floating diffusion node and having a gate to which a ramp signal is input, and a reset transistor resetting the photodiode and the floating diffusion node. The method may include generating photo-generated charges at the photodiode, transferring the photo-generated charges to the floating diffusion node in response to a ramp signal; and resetting a reset electron potential of the photodiode to be higher than a reset electron potential of the floating diffusion node.