This study introduces a decision-making support method for maintenance activities of bridges after earthquake. A seismic damage prediction system for bridges which do not have seismic acceleration sensors was developed to support the maintenance activities. The system consists of two main modules, one is seismic load estimation module based on the data from seismic stations and the other is seismic damage prediction modules based on the finite elements analysis models for seismic analysis. After verifying the prediction system for the damaged bridges after Po-Hang Earthquake, it was found that the system was able to predict seismic damages of bridges enough to make a decision of maintenance activities.