The L 2,3 X-ray emission spectra of Cu metal and its oxides (Cu 2 O and CuO) have been measured by using monochromatic synchrotron radiation. From the analysis of spectra recorded at different excitation energies, the Lβ 1 /Lα 1,2 X-ray emission intensity ratio, i.e., I(L 2 )/I(L 3 ) is discussed. The intensity ratio, I(L 2 )/I(L 3 ) is found to show significant enhancements for the compound materials such as Cu 2 O and CuO, at resonance energy. At non-resonant high energy, I(L 2 )/I(L 3 ) for CuO is observed to be higher than those for Cu and Cu 2 O. These tendencies are explained to be resonant or non-resonant excitation/deexcitation processes and absorption coefficients, including the chemical bonding effects.