Using a density-functional electronic structure calculation method, the electronic structure of an isolated C-60 molecule are calculated under consideration of finite external electric fields, and changes in electron density induced by the external electric fields are investigated in detail. Main finding of this study is that field-induced change in the electron density of an isolated C-60 molecule significantly differs depending oil molecular orientation relative to electric field direction, even though the field-induced total dipole moment of a whole molecule hardly shows such orientational dependence. Moreover, such orientational dependence also arises both in total energy and in dielectric constant. These orientational dependence would affect the chemical reactivity and orientational preference of rotating C-60 Molecules in a gas phase under finite external electric fields. (C) 2007 Elsevier B.V. All rights reserved.