Behavior analysis and modeling of entities is discussed as one of practical methods for data oriented approach to systems design. For this purpose, the notions of normalization and abstraction of entities are introduced to refine conceptual Schemas in the framework of the ER(Entity-Relationship) model. Behavior of entities, which is defined as a set of states and transactions that bring about state transitions, is analyzed and modeled using the ER model and diagrammatic techniques of Petri Nets. A formalization of behavior description, together with the notion of transaction normalization, is also proposed. Based on the behavior modeling, an idea for data oriented approach to information systems design is discussed.