There is provided a multi-stage CMOS power amplifier including: a driver amplifier having differential output terminals, inverting differential signals input through first and second input terminals and outputting the respective inverted signals through the differential output terminals; a transformer for power matching having a primary coil connected between the differential output terminals of the driver amplifier and a secondary coil coupled with the primary coil using electromagnetic induction, having a predetermined turns ratio to the primary coil, and connected to a direct current (DC) tuning voltage terminal; and a power amplifier power-amplifying differential signals passing through one end and the other end of the secondary coil of the transformer and outputting the respective power-amplified differential signals through first and second output terminals.