ABSTRAK Telah dilakukan penelitian tentang aplikasi metode geomagnetik untuk investigasi sisa benteng Lubok di kawasan Lamreh, Aceh Besar. Penelitian ini bertujuan untuk memetakan sisa benteng Lubok yang terkubur dengan mengukur intensitas total medan magetik. Alat yang digunakan adalah Magnetometer G-856 jenis Proton Precession Magnetometer (PPM). Untuk mendapatkan informasi spasial sisa bangunan secara keseluruhan pengukuran dibuat 23 lintasan yang membujur Utara Selatan dalam kawasan Benteng. Jarak antar lintasan 5 meter dan jarak antar titik pengukuran 3 – 5 meter. Setelah dilakukan koreksi variasi harian dan International Geomagnetic Reference Field (IGRF) pada data pengukuran, diperoleh anomali medan magnetik total. Anomali residual diperoleh setelah data anomali regional diangkat sehingga didapat gambaran struktur dangkal pada lokasi penelitian. Bentuk sisa bangunan benteng ditandai oleh pola-pola kelurusan yang membujur dari Utara ke Selatan di sisi kiri dan kanan dan arah Timur - Barat pada sisi Utara dan Selatan. Berdasarkan interpretasi kualitatif, benteng Lubok telah dapat dipetakan dan direkontruksi ulang dalam bentuk persegi dengan ukuran panjang benteng 90 meter, lebar 40 meter, tebal 5 meter dan kedalaman 5 meter. Katakunci: metode magnetik, arkeologi geofisika, anomali medan magnetik total, Kerajaan Aceh, benteng. ABSTRACT Archeological site of Lubok’s Fortress at Lamreh, District of Aceh Besar, has been investigated using magnetic method. Aim of this study is to map part of the fortress construction that has been buried in the ground. We measured intensity of magnetic total on the area using Proton Precession Magnetometer (PPM) G-856. In order to cover spatial information of the site, we collected the data along 23 profiles crossing the site. Distance between the profiles is 5 meter and stations spacing vary from 3 to 5 meter. Total magnetic anomalies were obtained after diurnal and International Geomagnetic Reference Field (IGRF) correction applied to the data. Residual and regional anomalies were separated in order to gather better information of near surface objects. Locations of buried construction of the fortress at shallow depths are clearly figured by parallel contours of the anomalies directed in South-North at the West and East sides and directed in East-West at the South and North sides of the area. Based on qualitative interpretation, location of the Lubok’s Fortress has been mapped successfully. We interpret shape the fortress was rectangular, i.e. 90 x 80 meter squares, thickness of the wall is about 5 meters, and buried less than 5 meters below subsurface. Keyword: magnetic method, geophysical archeology, total field anomalies, Aceh Sultanate, fortress.