Provided herein may be an image sensor and a signal conversion method. A signal transducer for converting an analog pixel signal into a digital signal may include an operational amplifier configured to receive a pixel signal, a conversion gain of which is changed, through a first input terminal, receive a ramp signal through a second input terminal, and change polarities of the first input terminal and the second input terminal based on an inverse signal, and a signal manager configured to generate the inverse signal in response to a change in the conversion gain and transfer the inverse signal to the operational amplifier.