This research has mapped the active fault of the Seulimeum segment part of the extension of The Great Sumatran Fault (GSF) in the northern as preparation for disaster mitigation. Nevertheless, seismic activity significantly on the Seulimeum segment still has not happened yet. This situation has the potential for a hugely destructive earthquake with a magnitude reaching ~7.4 and also will threaten the Weh island at the northernmost end of the Seulimeum segment even though the Weh island is a settlement, integrated economy area, tourism, trade area, and freeport zone. This study used geophysical methods, i.e., geomagnetic methods, for subsurface investigation. Each distance of 500m data was measured throughout the island using the Proton Precession Magnetometer (PPM) GEM 19 to get 204 total magnetic field data. The correction process (e.g., diurnal and IGRF) is done to get the total intensity of magnetic anomalies. Based on the calculation of residual data and analytical signals from the intensity of total magnetic anomalies, Interpretation found 13 fault distributions around the island with orientation in the northwest-southeast. This result has in agreement with the previous studies. However, this research has did not yet got information about geometry and fault depth. Comprehensive research is needed to complete it.