A feed forward microwave power amplifier having a divider for dividing an input signal into two parts, a first main amplifier for amplifying one of the divided signals, means for providing a part of the output of the first amplifier as a signal S.sub.1, means for providing a signal S.sub.2 by another output of the divider, a subtractor for providing the difference between S.sub.2 and S.sub.1, a second amplifier having the same gain as that of the first amplifier for amplifying this difference, a 3 dB coupler for coupling an output S.sub.4 of the first amplifier and an output S.sub.4 e, where e is a constant, of the second amplifier to provide coupled power which is free from distortion, and adjusting means for adjusting the level of signals S.sub.1 and S.sub.2 so that S.sub.2 is higher than S.sub.1, and the value e is in the range between 0.2 and 0.5. The particular features of the present invention, compared with a prior feed forward amplifier, are the use of a 3 dB coupler, and the configuration of the second amplifier which accepts not only the distortion component but also some desired component of the output of the first amplifier.