Super-multi-span Continuous Menshin (Menshin means Seismic Isolation in Japanese [Sugita et aJ. (1994)]) Bridges with bridge lengths of over 1,000 m increase (Iriving comfort, mitigate maintenance by saving the number of expansion joints, and reduce the inertia force of the superstructure which is transmitted to the substructure during earthquakes. In designing the super-multi-span continuous bridges, there are several subjects to be investigated such as the limitation of continuous girder length, effect of the change of the ground condition in a bridge on the earthquake response characteristics, effect of the spatial difference of the earthquake ground motion and so on. In this paper, the limitation of the continuous girder length was studied through the trial designs of three kinds .of girder bridges. Then the effects of the change of ground condition and the variation of the earthquake ground motion were studied through the dynamic response analyses. Based on these studies, key issues for the seismic design of super-multi-span continuous Menshin bridges were summarized.