This paper provides a new approach of manipulability for general grasping system. While conventional manipulability is the analysis in velocity domain and can not include force effect such as gravitational force, the proposing approach can include the force effect to keep grasping. For the purpose, an operation range is introduced. The operation range is for actuator attached with every joint of robot and provides generable joint torque and velocity and their relation (between generating torque/velocity and addable velocity/torque). Using the operation range, we derive manipulability set and measure in velocity domain, including force effect. The proposing method can evaluate not only the performance in velocity domain but also effects of friction, contact state, and external forces, which were not obtained in conventional studies.