Bridge bearings are the structural members which are installed at the connection between superstructure and substructure in a bridge. They are expected to transfer load between superstructure and substructure, and to accommodate expansion and rotation of superstructure due to live load and temperature change. Bridges are designed based on whole structure models in which bearings show perfect performance. If bearings are deteriorated, the structure system of the whole bridge should be changed, and some damage may occur in superstructure and substructure. Therefore, it is of great importance to maintain bearings in good conditions. In this study, we try to establish quantitative evaluation method for required basic functions (load supporting, horizontal moving and rotating function) of bridge bearings as the structural member, through measuring displacement and stress in several highway bridges in the north area of Japan.