This paper proposes a RSSI of geomagnetic field-based indoor positioning method that takes advantage of the dependence of RSSI of geomagnetic field on the type of building material. Buildings are usually constructed with H-beam or reinforced concrete. However, most researches on RSSI of geomagnetic field-based indoor positioning do not consider the extent of geomagnetic field disturbance by building material. Based on the finding that RSSI of geomagnetic field is more affected by H-beam building than reinforced concrete building, and by applying interpolation, the proposed positioning method achieved efficient database generation. Experiments demonstrated that the proposed method not only efficiently reduced DB generation costs but also was faster.