  Quantization of the pure $1+1$ dimensional dilaton gravity is examined in the
light-cone gauge. It is found that the total action including ghosts generates
a $c=0$ free conformal field theory without modification of the classical
action, which is required in the conformal gauge. We also study semiclassical
equations of the dilaton gravity coupled to $N$ scalar fields. It is shown that
the black hole singularity is not removed even for $N<24$ in the light-cone
gauge. This indicates that the semiclassical analysis breaks down for small
$N$.
