Minor deterioration of bearings is not expected to affect the entire bridge system in case of any seismic activity. However, past studies have reported that as the stiffness of bearings increases, the damping decreases with the increase in deterioration. In this study, we investigated the effect of the change in stiffness and damping on the seismic resistance of the bridge. The displacement response of bearings and piers for robust and deteriorated bearings were calculated using a two-degree-of-freedom analytical model based on actual seismic data of JMA magnitude 6 or greater in Japan. Furthermore, the shear strain of bearings and the ductility factor of piers were compared with respect to peak ground acceleration and peak ground velocity. Based on these results, the fragility curves of the bearings and piers against earthquake acceleration and velocity were calculated using actual seismic data. Additionally, the cost of the bridge to be incurred was also evaluated when the disaster happened. A risk assessment of earthquake velocity was performed for the entire highway bridge system model considering the probability of occurrence at the bridge location. Therefore, we found that the aging of the bearings increased the probability of rupture of the piers during an earthquake, and the fragility characteristics indicated that the piers were affected by the aging of the bearings. We were able to calculate the probable maximum loss of highway, considering the recovery cost, loss of highway toll, travel time, and human casualties.