A transmitter suppresses a peak level of a multi-carrier signal produced by synthesizing a plurality of carrier signals. Specifically, a peak level suppression signal for a multi-carrier signal is generated. The generated peak level suppression signal is adjusted in accordance with the levels of respective carriers constituting the multi-carrier signal. And, the adjusted peak level suppression signal for each carrier is subtracted from an input signal, thereby generating a multi-carrier signal whose peak level is suppressed.