A multi-functional cyclic silicate compound, a siloxane-based polymer prepared from the silicate compound and a process of producing an insulating film using the siloxane-based polymer. The silicate compound of the present invention is highly compatible with conventional pore-generating substances and hardly hygroscopic, so it is useful for the preparation of a siloxane-based polymer suitable to a SOG process. Furthermore, a film produced by the use of such siloxane-based polymer is excellent in mechanical properties, thermal stability and crack resistance and enhanced in insulating properties by virtue of its low hygroscopicity. Therefore, in the field of semiconductor production, this film is of great use as an insulating film.