a transmission unit for outputting a transmission signal of a plurality of transmission modes in which transmission power characteristics varies depending on the transmission mode and transmission power level is controlled by an AGC (Automatic Gain Control) signal;

a detection unit which generates an APC (Automatic Power Control) signal as a detection result of transmission power detection of said transmission signal outputted from the transmission unit; and

a processing unit which performs transmission power adjustment of said transmission signal of respective transmission modes by varying the AGC signal to be supplied to the transmission unit based on the APC signal of said detection result outputted from the detection unit,

wherein said processing unit includes:

first power adjustment means for performing a first power adjustment, by using a transmission power measuring instrument connected temporarily to the radio transmitter in which transmission power of the transmission signal of a specific transmission mode among the plurality of transmission modes is so adjusted that an error between a transmission power measured with the transmission power measuring instrument and a prescribed transmission power becomes not more than a prescribed value by varying the AGC signal to be supplied to the transmission unit, and storing an APC signal value at a time when the first power adjustment has completed as a first standard APC signal value;

second power adjustment means for performing a second power adjustment in which transmission power of the transmission signal of respective transmission modes other than the specific transmission mode is so adjusted that a difference between an APC signal value corresponding to the transmission power of the transmission signal of respective transmission modes other than the specific transmission mode being adjusted and the first standard APC signal value falls within a prescribed range by performing a feedback control of varying the AGC signal to be supplied to the transmission unit, and stores an APC signal value at a time when the second power adjustment has completed as a second standard APC signal value; and

third power adjustment means for performing a third power adjustment in which transmission power of an actual data transmission signal of a desired transmission mode is so adjusted that an error between an APC signal value corresponding to the transmission power of the actual data transmission signal and one of the first standard APC signal value and the second APC signal value corresponding to the desired transmission mode becomes not more than a predetermined value by performing a feedback control of varying the AGC signal to be supplied to the transmission unit.