  We summarize our renormalization group approach for the vector model as well
as the matrix model which are the discretized quantum gravity in one- and
two-dimensional spacetime. A difference equation is obtained which relates free
energies for neighboring values of $N$. The reparametrization freedom in field
space is formulated by means of the loop equation. The reparametrization
identities reduce the flow in the infinite dimensional coupling constant space
to that in finite dimensions. The matrix model gives a nonlinear differential
equation as an effective renormalization group equation. The fixed point and
the susceptibility exponents can be determined even for the matrix models in
spite of the nonlinearity. They agree with the exact result.
