Ship performance monitoring technology which is able to detect the change of ship performance is being developed in shipbuilding field. Although this technology has a possibility of enabling to set appropriate maintenance period, the ways of setting rule and evaluating economic value are not established. In this study, the way of maximizing the economic value of the fouling monitoring technology for ship hull and propeller is proposed, considering options of the maintenance rule. In order to set optimal maintenance rule, simulation was conducted considering maritime market, meteorology and operation.