  In order to promote our understanding on electronic structure of actinide
dioxides, we construct a tight-binding model composed of actinide $5f$ and
oxygen $2p$ electrons, which is called $f$-$p$ model. After the diagonalization
of the $f$-$p$ model, we compare the eigenenergies in the first Brillouin zone
with the results of relativistic band-structure calculations. Here we emphasize
a key role of $f$-$p$ hybridization in order to understand the electronic
structure of actinide dioxides. In particular, it is found that the position of
energy levels of $\Gamma_7$ and $\Gamma_8$ states determined from crystalline
electric field potentials depends on the $f$-$p$ hybridization. We clarify the
condition on the $f$-$p$ hybridization to explain the electronic structure
which is consistent with the local crystalline electric field state. We briefly
discuss the region of the absolute values of the Slater-Koster integrals for
$f$-$p$ hybridization concerning the appearance of octupole ordering in
NpO$_2$.
