The current bridge visual inspection system in Taiwan was introduced in this paper. According to the collected visual inspected information, a further analysis was adopted to propose a criterion for prioritization of bridge maintenance. A bridge is composed of 20 components which are evaluated with DERU method. For each damaged component, corresponding maintaining methodology is recommended and its amount is estimated. All of the healthy conditions of bridge components are summarized as a 'structural index', combining the other three indices of 'serviceability index', 'vulnerable index' and 'distinctive index' into a comprehensive Maintenance Priority Index (MPI) result. Three different field cases were discussed in this paper. A list of emergent bridges was clearly observed as getting their MPI rating results. Consequently, the optimum bridge maintaining strategy was promising to be set by sorting the priority with MPI rating, and the limited resource can meet the largest benefit.