  Hall effects are investigated for three-dimensional Dirac electrons as a
model of bismuth alloys. It is found that there is unconventional contributions
to the Hall conductivity $\sigma_{xy}$ generated by the interband effects of a
magnetic field. This phenomena is remarkable near the band-edge. The Hall
coefficient exhibits two unexpected properties; a sharp peak at around the
band-edges, and a drastic sign change in the band gap region. Implications of
the present results to bismuth alloys are discussed.
