An ADK is attachable to and removable from a VP and issues an instruction for autonomous driving to the VP. The VP includes a steering system for steering of the VP. (An ADS of) the ADK includes a compute assembly and a communication module configured to communicate with the VP. The compute assembly obtains from the VP, a torque value relating to a steering system 33 through the communication module and transmits to the VP, a wheel steer angle command indicating the wheel steer angle in accordance with a driving plan for autonomous driving and the obtained torque value. Even when a user intervenes with an operation while the attachable and removable ADK that issues the instruction for autonomous driving controls the VP, stable steering can be achieved.