Abstract: An automatic power control apparatus for use in a radio communication system employing a Time Division Multiplexing Access (TDMA) system according to the present invention has a level varying unit for amplifying a modulated wave that is output from a transmitter at an amplification factor specified by an external device, a level detecting unit for detecting a power level of a modulated wave, a computing unit for computing a power level of a non-modulated wave which is varied by a modulated wave obtained by linearly modulating a carrier wave in response to a modulation signal generated based on digital data, and a comparing unit that is used for comparing power levels. In the automatic power control apparatus, and amplification factor of the level varying unit is adjusted so that the power levels compared by the comparing unit become equal to each other during a transmission period of the non-modulated wave.