Abstract: Provided is an apparatus and method for calibrating a signal, which extracts a plurality of signal samples from sine-wave input signals; calculates a real root of a DC component calculating condition derived using simultaneous equations for values of the signal samples; calculates a value of a DC component from the simultaneous equations by using the calculated real root; and removes the DC component by applying the calculated value of the DC component to the sine-wave input signals, wherein the number of signal samples extracted in the signal sample extracting step is set according to the number of unknown quantities of the simultaneous equations.