Recently, dynamic behaviors in embedded system for ubiquitous environment and service-oriented system have needed a dynamic coupling metric to evaluate the quality of the software system more accurately. The embedded systems are designed by a component-based system and the component-based system is designed by one object-oriented. Therefore, coupling between the classes in the object-oriented model are brought into relief more clearly. But, in spite of a great deal of study and effort, most coupling metrics between classes suggest metrics that measure the coupling based on a static dependency relationship. In this paper, we propose a dynamic coupling metric in order to measure the coupling accurately between classes allowing the dynamic property in the object level. In addition, we prove the theoretical soundness of the proposed metric by the axioms of Briand et al. and suggest the accuracy of the proposed metric through a comparison with conventional metrics.