  In this paper, we study the lepton number violation processes of $B_c$ meson
induced by possible doubly-charged scalars. Both the three-body decay channels
and the four-body decay channels are considered. For the former,
$Br\times\left(\frac{s_\Delta h_{ij}}{M_\Delta^2}\right)^{-2}$ is of the order
of $10^{-7}\sim 10^{-9}$, and for the later channels,
$Br\times\left(\frac{s_\Delta h_{ij}}{M_\Delta^2}\right)^{-2}$ is of the order
of $10^{-12}\sim 10^{-20}$, where $s_\Delta$, $h_{ij}$, $M_\Delta$ are the
constants related to the doubly-charged boson.
