An on-die termination control unit turns on/off a corresponding transistor according to a code signal and adjusts an on-die termination resistance so it is equal to an external resistance. An offset compensating unit detects an offset voltage from an output voltage of the on-die termination control unit, stores the detected offset voltage in a capacitor, compares the capacitor voltage canceled the offset voltage with a preset reference voltage, and outputs the comparison result. A latch stores the output of the offset compensating unit for a predetermined time. A counter counts the output of the latch and increases or decreases the code signal.