  The resonances $D_{sJ}^*$(2317) and $D_{sJ}$(2460) which are considered to be
the $(0^+,1^+)$ doublet composed of charm and strange quarks have been
discovered recently. Using the method of Rosner which is based on the
factorization hypothesis, we calculate the lower bounds of the decay constants
of these states from the branching ratios of $B\to D D_{sJ}$ measured by Belle
and Babar.Our result shows that the decay constant of $D_{sJ}$(2460) is about
twice that of $D_{sJ}^*$(2317) on the contrary to the naive expectation of the
heavy quark symmetry which gives their equality. We show that this big
deviation originates from the large internal motion of quarks inside these
$P$-wave states and that our result is in good accord with the relativistic
quark model calculation.
