Abstract: A device for compensating for the nonlinearity of a power amplifier which has a simple configuration and can precisely linearize the transfer characteristics of the power amplifier by predistorting an input signal of the power amplifier. The nonlinearity compensation device of the present invention converts an RF input signal into an IF band rather than a baseband and predistorts the RF input signal in digital domain, and thus any modulation or demodulation process is obviated and the simultaneous processing of signals in multiple channels is facilitated. A first downconverter receives the RF input signal and converts the frequency band of the signal into the IF band to output an IF input signal. A predistortion unit receives and predistorts the IF input signal to compensate for the nonlinearity, and outputs an IF predistorted signal. An upconverter converts the frequency band of the IF predistorted signal into the RF band to provide such a signal to the amplifier.