There are disaster-fragile areas where old buildings are densely located and infrastructures are very poor. The areas have not been developed for many years just by private initiative so that they result in serious urban issues. This paper models such a situation so as to examine the effects of urban development policies. The model is based on the concept of self-fulfilling equilibrium with choice of development timing. According to Benefit Incidence Table Approach, we showed that social net benefit of urban development policies consists of the construction cost, the business cost burdened by the landowners and the benefit of the disaster prevention performance improvement enjoyable for the building users in the whole disaster-fragile area.