  Using the canonical formalism for spherically symmetric black hole inside the
apparent horizon we investigate the mass inflation in the
Reissner-Nordstr$\ddot o$m black hole in the framework of quantum gravity. It
is shown that like in classical gravity the combination of the effects of the
influx coming from the past null infinity and the outflux backscattered by the
black hole's curvature causes the mass inflation even in quantum gravity. The
results indicate that the effects of quantum gravity neither alter the
classical picture of the mass inflation nor prevent the formation of the mass
inflation singularity.
