Hospital administration is very important and many hospitals carry out activity-based costing under comprehensive medicine. However, nursing cost is unclear, because nursing practice is expanding both quantitatively and qualitatively and it is difficult to grasp all nursing practices, and nursing cost is calculated in many cases comprehensively. On the other hand, a nursing information system (NIS) is implemented in many hospitals in Japan and we are beginning to get nursing practical data. In this paper, we propose a nursing cost accounting model and we simulate a cost by nursing contribution using NIS data.