A self-location estimation method comprising: detecting a traffic sign in a vicinity of a vehicle; determining a current location of the vehicle; acquiring height information of the detected traffic sign from map data in which two-dimensional coordinate information of lane boundary lines (21a, 21b, 22a, 22b) of roads (21, 22) and two-dimensional coordinate information and height information of a traffic sign (23, 24) existing in a vicinity of the roads (21, 22) are recorded, based on a relative location of the detected traffic sign with respect to the vehicle and the current location; setting a target travel trajectory of the vehicle based on the map data and the two-dimensional coordinate of the current location of the vehicle such that the vehicle travels along a route on a two-dimensional coordinate system generated by a navigation system on a road of a plurality of roads (21, 22) on which the vehicle is present; and driving an actuator to operate a steering mechanism of the vehicle such that the vehicle travels on the target travel trajectory; and characterized by determining, when the plurality of roads (21, 22) the heights of which are different from each other exist at the two-dimensional coordinate of the current location of the vehicle, on which one of the plurality of roads (21, 22) the detected traffic sign is installed, based on the height information acquired from the map data, whereby the height information is information on which one of a plurality of different roads a traffic sign, among traffic signs respectively installed on the plurality of roads, that the traffic sign detected by the vehicle matches, is installed, and determining on which one of the plurality of roads (21, 22) the vehicle is present, based on on which one of the plurality of roads (21, 22) the detected traffic sign is installed. detecting a traffic sign in a vicinity of a vehicle; determining a current location of the vehicle; acquiring height information of the detected traffic sign from map data in which two-dimensional coordinate information of lane boundary lines (21a, 21b, 22a, 22b) of roads (21, 22) and two-dimensional coordinate information and height information of a traffic sign (23, 24) existing in a vicinity of the roads (21, 22) are recorded, based on a relative location of the detected traffic sign with respect to the vehicle and the current location; setting a target travel trajectory of the vehicle based on the map data and the two-dimensional coordinate of the current location of the vehicle such that the vehicle travels along a route on a two-dimensional coordinate system generated by a navigation system on a road of a plurality of roads (21, 22) on which the vehicle is present; and driving an actuator to operate a steering mechanism of the vehicle such that the vehicle travels on the target travel trajectory; and characterized by determining, when the plurality of roads (21, 22) the heights of which are different from each other exist at the two-dimensional coordinate of the current location of the vehicle, on which one of the plurality of roads (21, 22) the detected traffic sign is installed, based on the height information acquired from the map data, whereby the height information is information on which one of a plurality of different roads a traffic sign, among traffic signs respectively installed on the plurality of roads, that the traffic sign detected by the vehicle matches, is installed, and determining on which one of the plurality of roads (21, 22) the vehicle is present, based on on which one of the plurality of roads (21, 22) the detected traffic sign is installed.