  In terms of the heavy chiral Lagrangian and the unitarized coupled-channel
scattering amplitude, interaction between the heavy meson and the light
pseudoscalar meson is studied. By looking for the pole of scattering matrix on
an appropriate Riemann sheet, a $DK$ bound state $D_{s0}^*$ with the mass of
$2.312\pm0.041$ GeV is found. This state can be associated as the narrow
$D_{sJ}^*(2317)$ state found recently. In the same way, a $B{\bar K}$ bound
state $B_{s0}^*$ is found, and its mass of $5.725\pm0.039$ GeV is predicted.
The spectra of $D_0^*$ and $B_0^*$ with $I=1/2$ are further investigated. One
broad and one narrow states are predicted in both charm and bottom sectors. The
coupling constants and decay widths of the predicted states are also
calculated.
