Increasing business competition in various fields formed the basis of this research. The hospital is a service company that has a purpose to earn income and social mission, so it takes a good management of particular management costing to controlling the level of fees. Good cost control will provide effectiveness and efficiency in the production cost so that the optimal profit can be obtained while of increasing business competition. Activity Based Costing System is the appropriate method in the calculation of the cost of the staple by tracing the activities of companies that give rise to operational costs. Cost driver used in this research is the number of long of stays, the number of inpatients, and the floor area of the room. The results of the calculation of the price of the inpatient service method using the ABC System on RSUD Dr. Harjono S. Kabupaten Ponorogo delivers lower (undercosting) have a difference price of Rp 251,594.466 for VIP Class, Rp 42,344.528, for the Class Utama, and Rp 19,154.1 for the Class I. Tariff calculation with higher results (overcosting) is amounting to Rp 34,066.88 for Class II and Rp 7,089.815 for Class III.