This study analyzed the changes of the Jang-gumegi wetland using multi-temporal aerial images, and proposed an objective method of delineating wetland boundaries. The result of the study indicated that the Jang-gumegi wetland were formed in paddy fields in the early 1900’s, and the number of households and paddy area continued to increase by the government’s 5-year plan for agricultural production enhancement and the baby boom thereafter. On the other hand, the study area gave up on agricultural production when the number of households decreased due to migration from rural to urban area after the 1980’s, and the fields have been abandoned since then. Meanwhile, the wetland boundaries were re-detected based on the location information by GPS and soil depth data and sediment samples were updated in the Jang-gumegi wetland. The soil depth between the regions was proportionated to the period of paddy cultivation, and the grain size of the sediment consisted mostly of clay, silt and partially sandy particles. This reflected poor drainage of paddy fields, and it indicated that the sediment supplied from the slope after fallow was deposited along a gentle slope. The derived result is expected to serve as a guideline for the establishment of preservation and management measures for abandoned paddy wetlands and a better methodology for wetland boundary settings.