In automated vehicles, the driver and the vehicle make a decision on the driving. However, there is no guarantee that drivers always agree or follow the system's decision. Drivers can reject the system's proposal or regain control, and it reduces the usefulness of automated vehicles. When a decision conflict happens, the vehicle can negotiate with the driver. Human-human communication depends on the individual's attitude and situation. Similarly, the negotiation style needs to differ depending on the context of conflict and the cause of disagreement. In this workshop, we address the negotiation approach to designing HMI and discuss considerations for applying the human-human negotiation style to human-automated vehicle interaction design. HMI design using a negotiation approach can address the decision conflict between humans and automation and expect enhancing trust and acceptance.