A power series predistorter of the present invention includes a delay path for delaying a signal, a distortion generation path having an N-th order distortion generator and a vector adjuster, a divider for dividing an input signal between the delay path and the distortion generation path, a combiner for combining the output signal of the delay path and the output signal of the distortion generation path, and a controller for controlling the vector adjuster. The controller includes a setting unit, a distortion component measurement unit, a minimum condition calculation unit, and a recording unit. The setting unit specifies the phase or amplitude value of the vector adjuster. The distortion component measurement unit measures the distortion component of a power amplifier. The minimum condition calculation unit obtains a phase or amplitude value that minimizes the distortion component by function approximation, using the magnitude of the distortion components corresponding to three or more phase or amplitude values specified for sampling by the setting unit.