Glass transition temperatures of poly(ethyl acrylate) ionomers neutralized with various cations were studied dynamic mechanically in terms of ion content and the type of cations. On one hand, it was found that with increasing ion content the matrix T(g)s increased linearly and identically regardless of the variety of cations. Thus, it is inferred that the type of cations did not affect the matrix T(g)s. On the other hand, in the plots of the cluster T(g)s vs (ion content x charge)/(distance between charges), it was observed that the cluster T(g)s were superimposed on the straight line. This result implies that the cluster T-g involving ion hopping is affected by the type of cations. It was also found that the ionic modulus did not change with the type of cations significantly. In addition, the small-angle X-ray study showed that with increasing the radius of a cation the distance between scattering centers increased. Thus, it was postulated that the restricted mobility layer became thicker slightly with the increasing size of a cation.