Acid Mine Drainage (AMD) is one of the serious environmental problems in mining activities with the expansion of coal production in Indonesia. Some studies suggest that rock weathering can affect AMD; however, the effects on AMD are different depending on the rock properties, the mining operation, and field conditions. In this study, sample analysis was performed to characterize the rock samples: sequential extraction by strong acids, slaking test. Based on the results, the rock samples have a potential to cause acidic water. Additionally, AMD could be promoted due to the disintegration of rocks by physical and chemical factors. Both factors which promote AMD were confirmed in the wetting and drying process. Therefore, AMD is promoted by both factors in the mining area while waste rocks are stored and weather, suggesting that the current system for the treatment of waste rocks is one of the triggers of AMD.