The electronic structure of chromium aluminum oxynitride has been investigated using resonant photoemission spectroscopy (RPES) and the discrete variational (DV)-Xalpha method. The RPES measurement of the electronic structure around the Cr 2P(3/2) absorption edges exhibited significant resonant interference behavior for Cr 3d valence electrons, whereas it exhibited small resonant interference behavior for N 2p valence electrons. Therefore this RPES method can be useful for analyzing the valence band of chromium aluminum oxynitride film. The top of the valence band predominantly consists of Cr 3d and a small amount of N 2p. The difference between the measured photoemission spectra of the valence band and the DV-Xalpha calculation of chromium aluminum oxynitride ranges from 0.47 to 3.62 eV. This difference is probaly caused by the Coulomb interactions between the d electrons of chromium and the structure of the amorphous film. Through the experimental and theoretical studies, the valence band structure of chromium aluminum oxynitride came to be understand in detail.