A variety of photoelectron and Auger-electron spectra of 1,1,1-trimethyltrichlorodisilane vapor (Cl3SiSi(CH3)3) were measured by using monochromatized synchrotron radiation and a hemispherical electron energy analyzer. The measured spectra were interpreted with the aid of some calculations by means of the outer valence Green's function (OVGF) method or the density-functional-theory (DFT) method. Since Cl3SiSi(CH3)3 consists of SiCl3 and Si(CH3)3 moieties, the experimental core-electron binding-energies were compared with those of tetrachlorosilane and tetramethylsilane (SiCl4 and Si(CH3)4, respectively). This comparison showed that electronic properties of Cl3SiSi(CH3)3 hold a close correlation with those of SiCl4 and Si(CH3)4. Si:L23VV, Cl:L23VV and C:KVV Auger-electron spectra of Cl3SiSi(CH3)3 also showed profiles close to those expected from the spectra of SiCl4 and Si(CH3)4. The results obtained here were discussed in conjunction with electronic relaxation leading to site-specific fragmentation.