Coral reefs and associated tropical near shore ecosystems have suffered massive, long-term changes in abundance, diversity, and habitat structure due to overfishing and pollution. Especially, global warming has led to the global decrease in coral reefs recently. Coral reef habitat can be a good indicator of environmental change in a tropical coastal area. Here, we quantitatively estimated changes of coral reefs distribution in terms of the areal extent using high spatial resolution satellite images combined with in situ measurement in Weno island, Chuuk lagoon of Federated States of Micronesia. Habitat maps were generated from two Kompsat -2 images which had been acquired on September 2008 and August 2010, respectively. Classification of the coral reefs habitat was achieved by an object-based approach and the resultant maps were used to calculate the areal extent of coral reefs for the changes among each time of analysis to be estimated. coral reefs recently. Coral reef habitat can be a good indicator of environmental change in a tropical coastal area. Here, we quantitatively estimated changes of coral reefs distribution in terms of the areal extent using high spatial resolution satellite images combined with in situ measurement in Weno island, Chuuk lagoon of Federated States of Micronesia. Habitat maps were generated from two Kompsat -2 images which had been acquired on September 2008 and August 2010, respectively. Classification of the coral reefs habitat was achieved by an object-based approach and the resultant maps were used to calculate the areal extent of coral reefs for the changes among each time of analysis to be estimated.