  The form factors of weak decays of $B_s$ mesons to ground state $D_s^{(*)}$
mesons as well as to their radial $D_s^{(*)}(2S)$ and orbital $D_{sJ}^{(*)}$
excitations are calculated in the framework of the relativistic quark model
based on the quasipotential approach. All relativistic effects, including
contributions of intermediate negative-energy states and boosts of the meson
wave functions, are consistently taken into account. As a result the form
factors are determined in the whole kinematical range without additional
phenomenological parametrizations and extrapolations. On this basis
semileptonic decay branching fractions are calculated. Two-body nonleptonic
$B_s$ decays are considered within the factorization approximation. The
obtained results agree well with available experimental data.
