Provided is a technology for improving accuracy in determining the next action. Travel history generator generates, for each driver, a travel history associating an environmental parameter indicating a travel environment through which a vehicle has previously traveled with an action selected by the driver in response to the environmental parameter. Acquisition unit acquires a travel history similar to a travel history of a current driver from among travel histories generated by travel history generator. Driver model generator generates a driver model based on the travel history acquired by acquisition unit. Determination unit determines the next action based on the driver model generated by driver model generator) and an environmental parameter indicating a current travel environment of the vehicle.