  We study some rare decays of $B_s$ meson governed by the quark level
transitions $ b \to s$, in the fourth generation model popularly known as SM4.
Recently it has been shown that SM4, which is a simple extension of the SM3,
can successfully explain several anomalies observed in the CP violation
parameters of $B$ and $B_s$ mesons. We find that in this model due to the
additional contributions coming from the heavy $t'$ quark in the loop, the
branching ratios and other observables in rare $B_s$ decays deviate
significantly from their SM values. Some of these modes are within the reach of
LHCb experiment and search for such channels are strongly argued.
