There is disclosed a feedforward amplifier for compensating for distortion produced in an amplifier. The feedforward amplifier controls the phase in a vector adjuster effectively. The feedforward amplifier has a first variable phase shifter PH1—1 or PH2—1 for varying the phase of a signal passed through the first variable phase shifter and a second variable phase shifter PH1—2 or PH2—2 for varying the signal passed through the first variable phase shifter in either or both of a distortion detection loop for detecting the distortion and a distortion compensation loop for compensating for the distortion. A phase control portion controls the amount of variation in phase in the first variable phase shifter and values of the amount of variation in phase are concentrated toward either one of relatively-larger directions or relatively-smaller directions, the amount of variation in phase in the second phase shifter is controlled according to the concentrated values.