  We investigate the interaction between flat membrane and point-like graviton
in the plane-wave matrix model. The one-loop effective potential in the large
distance limit is computed and is shown to be of r^{-3} type where r is the
distance between two objects. This type of interaction has been interpreted as
the one incorporating the smearing effect due to the configuration of flat
membrane in plane-wave background. Our result supports this interpretation and
provides one more evidence about it.
