Photoluminescence (PL) and piezoelectric photoacoustic (PPA) spectra have been studied at low temperatures for nondoped and N-doped ZnSe epitaxial layers grown by molecular beam epitaxy. Deep emission bands observed in nondoped ZnSe are disappeared with nitrogen doping in the PL spectra. On the other hand, new nonradiative signals appear with nitrogen doping in the PPA spectra. This indicated that nonradiative carrier recombination centers are introduced by the nitrogen doping process in molecular beam epitaxy growth.