We calculated the nuclear reactor antineutrino spectrum on the basis of nuclear data libraries (JENDL-3.2, JNDC-V2). The antineutrino spectrum was first calculated with neglecting energy dependence of matrix element, and the result had tendency to be larger than the experimental data in the high energy region. We introduced an adjustable parameter for correcting the spectrum calculation. The method gives a good agreement between calculated and experimental spectra.