Variation of damping capacity with aging time in an Fe-17%Mn alloy with different carbon contents has been studied from the kinetic viewpoint. The average of decreasing velocity of damping capacity at each aging temperature increases with increasing carbon content and reaches maximum around 0.12wt%C, and then decreases with further carbon content. This indicates that the decreasing velocity of damping capacity can be represented by an equation V_ｄ= K·A_d·C_s, where K is constant, .A_d the total interfacial area of damping sources per unit volume, and C_s the amount of carbon segregated at damping sources. The activation energy for the damping decrease process is 6 ㎉/㏖ regardless of the carbon content. Such a small activation energy suggests that carbon segregation at damping sources is caused by interaction of carbon atoms with damping sources without long range diffusion of carbon atoms through lattices.