A distortion compensator, includes: an input terminal configured to receive a transmission signal; a processor configured to perform operations to process the transmission signal, wherein the operations includes: compensating a nonlinear distortion of an amplifier which amplifies a power of the transmission signal, by using a distortion compensation coefficient corresponding to an amplitude value of the transmission signal; calculating a difference between a power value of the transmission signal and a power value of a feedback signal from the amplifier; calculating an imaginary part of a first complex vector based on an error between the transmission signal and the feedback signal in a cartesian coordinate system; and updating the distortion compensation coefficient by using a second complex vector of which a real part is the difference, and an imaginary part is the imaginary part of the first complex vector.
