Suggested in this study are methods of reasonably evaluating the dynamic characteristics of the bridge gy use of the measured acceleration signal. As for the analytical method, quantitatively transformed by use of system identification technic in the modal coordinates was structural uncertainty making the difference between the actual measurements and the FEM analysis results, wherefrom improvement of dynamic structural models could be achieved. The improved dynamic structural models can generate the dynamic model that coincides with the actual measurements by taking into account the dynamic characteristics of structure. And in order to confirm the feasibility of the improving method of dynamic structural models of the bridge in consideration of the structural uncertainty, application was done th the simple slab bridge and tentatively to the continuous bridge. As a results, dynamic characteristics of the structures-such as natural frequency and modal parameter-can be obtained improved dynamic structural models suggested in this study.