We have studied theoretically the electronic structures of a hypothetical donor-type material, (PH4)(3)C-60, and a hypothetical acceptor-type material, (ClO4)(3)C-60 from first principles by using a full-potential linear-combination-of-atomic-orbitals method based on the density-functional theory within the local-density approximation. It is found that the charge transfer from the PH4 molecules to the C-60 molecules is perfect while the charge transfer from the ClO4 molecules to the C-60 molecules is not perfect. We compare the latter result with the electronic structures of two typical acceptor-type organic conductors, (TMTSF)(2)ClO4 and (TMTSF)(2)PF6, and discuss the differences.