[en] Using neutron and resonant X-ray scattering, we studied crystal structure and charge-ordering pattern in La_1.5Ca_0.5CoO₄. Taking A2mm with a-b type twin structure into account, Co²⁺/Co³⁺ checkerboard charge ordering pattern was suggested in La_1.5Ca_0.5CoO₄ by neutron scattering structure analysis. In order to clarify the charge ordering pattern and the valences of the two Co sites, we performed a resonant X-ray scattering (RXS) measurement near the Co K-edge. We found a resonant signal at (3, 0, 0) reflection within corresponds to the charge ordering with a Co²⁺/Co³⁺ checkerboard pattern, and the Co valences of charge ordering were fully charge disproportionated. From the X-ray fluorescence spectra, we found the pre-edge peak structures at E=7.710 and 7.713 keV, corresponding to 1s → t_2g and 1s → e_g transitions, respectively. The polarization dependence of the latter one suggests that the anisotropy e_g orbital is realized in La_1.5Ca_0.5CoO₄. (author)