  Recently, the magnetar Swift J1834.9$-$0846 is reported to have a possible
wind nebula. It is shown that both the magnetar and its wind nebula are
understandable in the wind braking scenario. The magnetar's rotational energy
loss rate is not enough to power the particle luminosity. The required particle
luminosity should be about $10^{36} \,\rm erg \,s^{-1}$ to $10^{38} \,\rm erg
\,s^{-1}$. It is obtained in three different approaches: considering wind
braking of Swift J1834.9$-$0846; the spectral and spatial observations of the
wind nebula; and an empirical upper bound on wind nebula X-ray luminosity. The
nebula magnetic field is about $10^{-4} \,\rm G$. The possible wind nebula of
Swift J1834.9$-$0846 should be a magnetar wind nebula. It is powered by the
magnetic energy release of the magnetar.
