Degradation and recovery of damping capacity in a Cu-65%Mn alloy have been studied. When the alloy was isothermally aged at 400℃, the highest damping capacity was observed after aging for 4 hours. In case when the alloy aged at 400℃ for 4 hours was maintained at 100℃, the damping capacity gradually decreased with time. The microstructural observations showed that the formation of subdomains and α-Mn precipitates are responsible for the degradation of damping capacity. When the degraded specimen was reheated at 250℃ for 30 minutes, the damping capacity was recovered considerably owing to the redistribution of impurity atoms, the extinction of subdomains and the release of damping sources from α-Mn precipitates during the repeated transformation, fcc↔fct.