1. A vehicle motion model generating device for generating a vehicle motion model that represents a motion state of a vehicle, comprising: a first recurrent neural network formed by connecting plural nodes so that an output of a node is input to another node in accordance with a predetermined coupling weight coefficient, comprising a loop feeding back an output of at least one node to at least one of said one node and a node other than said one node; and an optimizing unit for determining an optimum solution of said coupling weight coefficient in said first recurrent neural network based on a learning rule using a hereditary algorithm, wherein said first recurrent neural network outputs a first parameter indicating said motion state of the vehicle based on predetermined input information, thereby functioning as said vehicle motion model.