Namasia nestles at northwest corner of Kaohsiung County; it is one of the three aboriginal townships in the municipality of Kaohsiung County. The township has residents of several different ethnic groups, but 70% of the population has Bunun origin, who mingle in the smaller communities of the Tsou, Atayal, Paiwan, and Han Chinese. Namasia is surrounded by mountains, which run across the township in the northeast direction. The ground is relatively high with a wider strip of mountain range at the west and slower hills at the south. The whole area is covered predominantly in hill land with partial stepping faults, riverbeds, and hillside terracing, and the terraces look like ladders in the basin. Overall, the township is surrounded by mountains, characterized by multi-level faults and terrace lands. The part is southern rounded, the central part has a wider strip, and the northern part is oblong, making the Basin shaped like a gourd.
Namasia Township is located at the northwest corner of Kaohsiung County and Tai 21 Expressway is a the main access road, which runs through three villages and connects to Tai 20 Expressway (the Southern Cross-Island Highway) at the 25 km mark to the southwest direction, linking Yujing at west and Taoyuan at east. The Township can also be accessed from Chiayi City southbound via Shanmei (Tanaiku Creek) and Chashan. Please see the access road system map for detailed information on the main access to Namasia.