In this paper, we introduce the detailed mapping on active fault in Nepal as a leading work on reduction for seismic hazard in developing region. Active faulting, is an origin of large earthquakes, causes tremendous damage for human life when it happens. However, developing countries have little understanding for nature of active fault and significance of the detailed active fault map for seismic hazard. We firstly show how to make the map. Then we enumerate two weak cases against faulting movement from the point of view of spatial relationship between the active fault and the infrastructures such as hydro-power station, the power lines and the bridge on the highway. Any infrastructure in Nepal is not considered to be located away from the fault. Some are too close to the fault to be dangerous if it moves. Judging from natural and social condition of Nepal, we propose significance of detailed active fault map for developing region. The map provides the precious location of the fault to keep the public infrastructure away from the fault. Because the number of infrastructure in developing resion is rarely and the function is subject to be concentrated at an existing infrastructure, if the fault moves, the damage hits not only the seismic area, but also its distant place extensively. As the map lets the local people to understand where the great earthquake is likely to happen, the map will be regards as a tool of the enlightenment of the seismic hazard.