  The problem of consistent definition of the quantum corrected gravitational
field is considered in the framework of the $S$-matrix method. Gauge dependence
of the one-particle-reducible part of the two-scalar-particle scattering
amplitude, with the help of which the potential is usually defined, is
investigated at the one-loop approximation. The $1/r^2$-terms in the potential,
which are of zero order in the Planck constant $\hbar,$ are shown to be
independent of the gauge parameter weighting the gauge condition in the action.
However, the $1/r^3$-terms, proportional to $\hbar,$ describing the first
proper quantum correction, are proved to be gauge-dependent. With the help of
the Slavnov identities, their dependence on the weighting parameter is
calculated explicitly. The reason the gauge dependence originates from is
briefly discussed.
