  Recently several experiments have reported evidences for pentaquark
$\Theta^+$. H1 experiment at HERA-B has also reported evidence for $\Theta_c$.
$\Theta^+$ is interpreted as a bound state of an $\bar s$ with other four light
quarks $udud$ which is a member of the anti-decuplet under flavor $SU(3)_f$.
While $\Theta_c$ is a state by replacing the $\bar s$ in $\Theta^+$ by a $\bar
c$. One can also form $\Theta_b$ by replacing the $\bar s$ by a $\bar b$. The
charmed and bottomed heavy pentaquarks form triplets and anti-sixtets under
$SU(3)_f$. We study decay processes involving at least one heavy pentaquark
using $SU(3)_f$ and estimate the decay widths for some decay modes. We find
several relations for heavy pentaquarks decay into another heavy pentaquark and
a $B (B^*)$ or a $D(D^*)$ which can be tested in the future. $B$ can decay
through weak interaction to charmed heavy pentaquarks. We also study some $B$
decay modes with a heavy pebtaquark in the final states. Experiments at the
current $B$ factories can provide important information about the heavy
pentaquark properties.
