An impedance control circuit includes a first impedance unit configured to terminate an impedance node using an impedance value that is determined by an impedance control code, a second impedance unit configured to terminate the impedance node using an impedance value that is determined by an impedance control voltage, a comparison circuit configured to compare a voltage level of the impedance node and a voltage level of a reference voltage, generate an up/down signal indicating whether the voltage at the impedance node is greater than the reference voltage, and generate the impedance control voltage that has a voltage level corresponding to a difference between the voltage at the impedance node and the reference voltage, and a counter unit configured to increase or decrease a value of the impedance control code in response to the up/down signal.