The control valve is one of the device which are the most important in a plant. Sudden trouble may lead to a drop of the production quality and a plant stop. There is the field devices of enormous numbers to the plant and has a hard time for check maintenance plan planning, enforcement for many customers to keep the normal function of the valve. A control valve diagnosis is useful for a help of the solution to this problem. Five diagnosis logics based on the field digital technology are equipped with for this diagnosis and contribute to the deterioration state detection of the valve. The diagnosis supports multi-vender and can diagnose a valve of the whole plant in the same diagnosis logic. Check maintenance plan planning in consideration of priority depending on a diagnosis result is possible.