This thesis discusses the accounting system of goods inventory whose aim is to find out the accounting system carried out by the regional drinking water company Tirta Satria Banyumas regency. Inventory accounting system is the most important system in running a busines inventory is a very inportant asset because the investment in inventory is usually the largest amount in all company investment. Inventory accounting system in the regional water supply company Tirta Satria Banyumas Regency is needed to do a job so that the implementation of the work is carried out systematically and not confusing. There is an internal control system to minimize the implementation.