Orientation of carbon fiber (CF) axes in poly(vinyl alcohol) (PVA) aqueous solution under magnetic field was evaluated by considering the fact that the c-axes (chain axes of graphite) have orientation distribution with respect to their CF axis. This new approach was proposed to resolve the well-known contradiction that the diffraction image from the (002) plane measured by X-ray shows broad arcs indicating dull orientation of the c-axes with respect to the magnetic field, whereas the corresponding orientation of CF axes observed by SEM reveals high predominant orientation. To pursue the quantitative evaluation, the orientation function of CF axes was obtained from the orientation function of the reciprocal lattice vector of the (002) plane by a somewhat coordinate transformation. The real orientation function of the CF axes with respect to the magnetic field direction showed very sharp distribution profile in comparison to the function of the c-axes and it was in good agreement with the orientation of CF axes observed directly by SEM. Furthermore, the orientation of CF axes up to the equilibrium state was estimated by a common diffusion equation. The calculated results predicted time dependence of the preferential orientation behavior of CFs in PVA solution precisely.