This study aimed to: 1) determine the mangrove vegetation change for the past 40-year; and 2) to verify the relationship of soil salinity, water pH and the distance from the shoreline of the mangrove Kandelia candel (L.) Druce with its height distribution along the river edges of Oura River in Minamitane, Tanegashima Island, Kagoshima Prefecture, Japan. Using GIS analysis and the application of ERDAS Imagine 8.5, the available archives data and the aerial photograph of the said area were rectified and digitized using Arc/Info and came up with the vector maps. Changes in mangrove forest cover were determined based on the 1961, 1977, 1988 available data and 2001 aerial photo. The study revealed a minimal deforestation of 1.53 ha. or 7.32% of its original area from 1961 to 2001. Changes were found mostly along the edges of the river and its tributaries where constructions have been made. The findings show that there are significant relationship between the level of soil salinity, water pH and the distance from the shoreline of the mangrove Kandelia candel with its height distribution in the 16 (5 m x 5 m) established plots. In areas where high levels of soil salinity and water pH have been recorded, the same trends of decreasing height were revealed. This research also revealed that the mangrove area has only one mangrove species - Kandelia candel.