Class extraction of object or component based software development methodology is the major factor for software quality. Each method has the class definition and extraction method however there are some troubles when the beginners try. Especially, the conceptual gap results to make the class extraction hard. This research suggests three diagrams to support it. They are Information diagram, Behavio diagram and Management diagram. They specify which services a stakeholder wants, which information to support the service, which actions to solve the service and who has the responsibility for those. Any analysis process which takes class extraction can utilize these diagrams.