Amplification and phase regeneration can be realized using a phase-sensitive amplifier (PSA). The phase regeneration of differential phase-shift keying (DPSK) signals based on PSA is analyzed theoretically. We realize the phase regeneration of differential quadrature phase-shift keying (DQPSK) signals based on a structure using two balanced PSAs. Simulations show that nearly ideal phase regeneration can be achieved for the DPSK/DQPSK signals.