  We study the simplicial quantum gravity in three dimensions. Motivated by the
Boulatov's model which generates a sum over simplicial complexes weighted with
the Turaev-Viro invariant, we introduce boundary operators in the simplicial
gravity associated to compact orientable surfaces. An amplitude of the boundary
operator is given by a sum over triangulations in the interior of the boundary
surface. It turns out that the amplitude solves the Schwinger-Dyson equation
even if we restrict the topology in the interior of the surface, as far as the
surface is non-degenerate. We propose a set of factorization conditions on the
amplitudes which singles out a solution associated to triangulations of $S^3$.
