An image sensor includes a photoelectric converter to generate charges in response to incident light and to provide the generated charges to a first node, a transfer transistor to provide a voltage of the first node to a floating diffusion node based on a first control signal, a source follower transistor to provide a voltage of the floating diffusion node as a unit pixel output, a correlated double sampler (CDS) to receive the unit pixel output and to convert the unit pixel output into a digital code. The first control signal having first, second, and third voltages is maintained at the second voltage in a period between when the voltage of the first node is provided to the floating diffusion node and when the CDS is provided with the voltage of the first node as the unit pixel output.