Theoretical formulae for the thermoelectric power of titanate and ferrite with cubic perovskite structures were presented as the carrier-localized system. The formula for titanate was derived from the configurational entropy of the electrons in the t(2g) states of the unoccupied Ti 3d states, whereas the formula for ferrite was derived from the entropy of the holes in the e(g) states of the occupied Fe 3d states. Both formulae were developed for a simple electron system. Assuming that the electrons and holes in the subbands are strongly localized at the Ti and Fe ions and that only Ti4+ and Ti3+ or Fe3+ and Fe4+ ions exist in the crystal, the formulae of the thermoelectric power are equivalent to the Heikes formula even though the orbitals in the subbands are triply and doubly degenerated.