  Lepton number violation processes can be induced by the Majorana neutrino
exchange, which provide evidence for the Majorana nature of neutrinos. In
addition to the natural explanation of the small neutrino masses, Type-I seesaw
mechanism predicts the existence of Majorana neutrinos. The aim of this work is
to study the B meson rare decays $B^{+} \to K^{(*)+}\mu^+\mu^-$ in the standard
model and its extensions, and then to investigate the same-sign decay processes
$B^{+}\to K^{(*)-}\mu^{+}\mu^+$. The corresponding dilepton invariant mass
distributions are predicted. It is found that the dilepton angular
distributions illustrate the properties of new interactions induced by the
Majorana neutrinos.
