A simple analysis model with two or four degrees of freedom was applied to a multi-span continuous girder bridge with an ants-seismic bearing in order to clarify its dynamic elasto-plastic behavior during an earthquake. The same structure was then nalyzed using a non-linear time history response method with a multiple degree of freedom, using a more detailed frame analysis model. When the dynamic behaviors obtained from both analysis methods were compared, no significant difference was observed between both response values. Thus, the effective application of this analysis method based on a simple analysis model to the mults-span continuous girder bridge was demonstrated.