A gravity survey of the island of Taiwan was carried out from 1980 to 1987. In a 7-year effort, 603 gravity stations, most of which are located on geodetic stations, have been established. The average spacing between the stations is about 7km. The Bouguer and terrain corrections were made over a distance range of 100km using an average density of 2.57g/cm3. After the reductions, the Bouguer anomaly map was constructed. In general, the isogals of the Bouguer anomaly map trend NNE in consonance with the overall structural trend of the island. Negative anomalies cover a major part of the island; positive anomalies dominate in the eastern part of the Central Range, the Coastal Range and the northern extremity of the island. A high gradient belt, parallel to the trend of the island, is observed in the eastern Central Range across the suture zone between the Philippine Sea and Eurasian plates. In addition, the gravity anomaly data suggests that the island of Taiwan is not in isostatic equilibrium.