  We analyze the effect of R-parity violation in the minimal supersymmetric
standard model on the CP asymmetries in $b\to s \gamma$ decay. The direct and
mixing-induced CP asymmetries arising from the lepton number violating
couplings are strongly constrained by the current experimental limits on the
corresponding couplings. Allowing a heavy neutrino ($m_{\nu_\tau}\sim10$ keV)
and a moderate mass splitting of sfermions, the direct CP asymmetry around 15 %
and the nearly maximal mixing-induced CP asymmetry ($\sim 100 %$) can be
realized, depending on the R-parity conserving contributions to the radiative
$b$ decay. With the baryon number violating couplings, only the mixing-induced
CP asymmetry arises and it can be maximal provided there is a the similar
sfermion mass splitting.
