  We present a new class of quantum two dimensional dilaton gravity model,
which is described by $SL(2,R)/U(1)$ gauged Wess-Zumino-Witten model deformed
by $(1,1)$-operator. We analyze the model by ${1 \over k}$ expansion ($k$ is
the level of $SL(2,R)$ Wess-Zumino-Witten model) and we find that the curvature
singularity does not appear when $k$ is large and the Bondi mass is bounded
from below. Furthermore, the rate of the Hawking radiation in the quantum black
hole created by shock wave goes to zero asymptotically and the radiation stops
when the Bondi mass vanishes.
