According to example embodiments, an image sensor includes a charge sensing amplifier (200) configured to amplify charges sensed by a sensing unit (110). The charge sensing amplifier includes an input terminal (IN), an amplification terminal (210), an output terminal, a first capacitor (C1) connected between the input terminal and the amplification terminal, a first switch (SW1) connected between the input terminal and the amplification terminal, a second capacitor (C2) connected between the amplification terminal and the output terminal, and a second switch (SW2) connected between the output terminal and a reference voltage terminal.