Abstract: On the basis of structural reliability theory, inspection/repair of reinforced concrete (RC) bridges is discussed to search for the most appropriate time and the best method for inspection and repair of bridges with minimum cost. The repair decision is based on the deterioration models of bridge structures. Necessity of additional inspection and measurement is evaluated before each decision on repair action. More information from the additional inspection and measurement serves better decisions. A planning procedure to optimize inspection/repair schedule is established on the basis of pre-posterior decision making method.