In the present paper, a vibration mode modification method when the dynamic characteristics of the vibration system change by assembly is proposed. When the dynamic characteristics change, component mode synthesis (CMS) is widely used. However, CMS is not suitable for vibration control. Therefore, the present paper proposes a component mode modification technique for vibration control problem. The vibration modes are modified using component modes for constructing a reduced-order model. In this method, vibration modes are modified using static correction modes (attachment modes). Using these modes, orthogonalization is performed by subspace iteration. First, the concept of vibration mode modification is proposed. This concept is then applied to the proposed modeling method, which is referred to as the extended reduced-order physical modeling method. Finally, the proposed method is examined through dynamic responses of an elastic vehicle. Using the elastic vehicle, a single lane change test and simulation are carried out.