According to example embodiments, an image sensor includes a charge sensing amplifier configured to amplify charges sensed by a sensing unit. The charge sensing amplifier includes an input terminal, an amplification terminal, an output terminal, a first capacitor connected between the input terminal and the amplification terminal, a first switch connected between the input terminal and the amplification terminal, a second capacitor connected between the amplification terminal and the output terminal, and a second switch connected between the output terminal and a reference voltage terminal.