For the perovskite-type cobalt fluoride of KCoF₃, cluster model calculations based on the spin-polarized Hartree-Fock (UHF) and hybrid-density functional theory (HUDFT) methods have been performed. It has the slightly tetragonally distorted structure, where cobalt is octahedrally surrounded by fluorine’s. In this study, we have examined the spin states under consideration of the ligand field effect, from the viewpoints of the spin density, charge density, total energy and effective exchange integral. [DOI: 10.1380/ejssnt.2007.17]