This invention relates to an organosilicon compound having a cyclic structure with nitrogen atom and silicon atom, and one or more sulfur atoms in its molecule, and having a bonding side of one or more groups having as small steric hindrance to silicon atom, a rubber composition formed by compounding an inorganic filler (B) and the organosilicon compound (C) into a rubber component (A) consisting of natural rubber and/or diene-based synthetic rubber, and a tire using such a rubber composition.