Fluorescence and its polarization spectra of phenylpentamethyldisilane (1) and its para-substituted derivatives (para-substituent: -C(CH3)(3) (2), -OCH3 (3), and -N(CH3)(2) (4)) were measured in a poly(vinyl alcohol) film at 77 K. Intramolecular charge transfer (ICT) fluorescence together with locally excited (LE) emission was found even for the compounds having an electron-donating substituent at the para-position (2 and 3) as well as that of 1. The ICT state of these compounds showed an in-plane long axis polarization. By the measurements of fluorescence lifetimes, it was found that there was no dynamic equilibrium between the ICT and LE states, indicating that the ICT state originates from the nonrelaxed excited singlet (S-n(7)) state. Ab initio MO calculations (CASSCF and MRMP methods) were performed for the ground and excited states of phenyldisilane with planar and perpendicular conformations. The following results were obtained: (I) upon excitation, the ICT of phenyldisilane occurs from the phenyl moiety to the disilanyl group regardless of planar or perpendicular conformation, (2) in the course of the ICT formation, conformational changes in the Si-dimethyl group adjacent to the phenyl group play an important role rather than a twisting motion of the disilanyl group, and (3) the ICT state consists of the pi,pi＇* state produced by ICT from the phenyl moiety to the disilanyl group, where pi＇* denotes the excited pseudo-pi orbital.