The comparison of the judgment of chemical bond strength by means of bond energy (E~A~B) and Mulliken's overlap population (M~A~B), has been discussed in this paper. The result shows that in most cases both E~A~B and M~A~B are consistent with experimental data qualitatively, with E~A~B being better than M~A~B on a quantitativebasis. In some cases, M~A~B is not compartible with experimental data even on a qualitative basis, whereas E~A~B is, both qualitatively and quatifatively. As a criterion for the character and the strength of chemical bond between atoms in a molecule, E~A~B is better than M~A~B, because both the overlap population factor between atomic orbitals and the energy factor of molecular or atomic orbitals are included in E~A~B.

Key words: BOND ENERGY, MOLECULAR ORBITAL THEORY