An anomaly detector for a self-location estimation device that is installed in a vehicle and is configured to estimate a self-location defined by an external coordinate system, the anomaly detector comprising: a first feature-point coordinate calculation section that is configured to measure, based on output from a first measuring device, a location of the vehicle relative to each feature point (Pa) in a feature point group on a surrounding structure around a road surface on which the vehicle travels, the feature points (Pa) of the feature point group being lined along a travel direction, to acquire coordinates of each feature point (Pa) expressed in a coordinate system of the first measuring device, and to use the self-location to convert the acquired coordinates into first coordinates in an external coordinate system; a feature-point trajectory generation section that is configured to generate, based on the first coordinates, a trajectory (Pa'_tr) defined by the external coordinate system of the feature point group by arranging the feature points (Pa) in a time sequence of measurements of the first coordinates; a second feature-point coordinate calculation section that is configured to measure, based on output from a second measuring device, a location of the vehicle relative to the feature points (Pb) in the feature point group of the surrounding structure, the feature points (Pb) being located, in the travel direction, rearward of the feature points (Pa) measured by the first measuring device, at a measurement time of the first measuring device, to acquire coordinates of the feature points (Pb) located rearward in the travel direction, the coordinates being expressed in a coordinate system of the second measuring device, and to use the self-location to convert the acquired coordinates into second coordinates in said external coordinate system; and an anomaly determination section that is configured to determine that anomaly occurs in the self-location estimation device if a deviation between the second coordinates and the trajectory (Pa'_tr) of the feature point group defined by the external coordinate system exceeds a threshold established to deem that the second coordinates are on the trajectory (Pa'_tr). a first feature-point coordinate calculation section that is configured to measure, based on output from a first measuring device, a location of the vehicle relative to each feature point (Pa) in a feature point group on a surrounding structure around a road surface on which the vehicle travels, the feature points (Pa) of the feature point group being lined along a travel direction, to acquire coordinates of each feature point (Pa) expressed in a coordinate system of the first measuring device, and to use the self-location to convert the acquired coordinates into first coordinates in an external coordinate system; to measure, based on output from a first measuring device, a location of the vehicle relative to each feature point (Pa) in a feature point group on a surrounding structure around a road surface on which the vehicle travels, the feature points (Pa) of the feature point group being lined along a travel direction, to acquire coordinates of each feature point (Pa) expressed in a coordinate system of the first measuring device, and to use the self-location to convert the acquired coordinates into first coordinates in an external coordinate system; a feature-point trajectory generation section that is configured to generate, based on the first coordinates, a trajectory (Pa'_tr) defined by the external coordinate system of the feature point group by arranging the feature points (Pa) in a time sequence of measurements of the first coordinates; a second feature-point coordinate calculation section that is configured to measure, based on output from a second measuring device, a location of the vehicle relative to the feature points (Pb) in the feature point group of the surrounding structure, the feature points (Pb) being located, in the travel direction, rearward of the feature points (Pa) measured by the first measuring device, at a measurement time of the first measuring device, to acquire coordinates of the feature points (Pb) located rearward in the travel direction, the coordinates being expressed in a coordinate system of the second measuring device, and to use the self-location to convert the acquired coordinates into second coordinates in said external coordinate system; and to measure, based on output from a second measuring device, a location of the vehicle relative to the feature points (Pb) in the feature point group of the surrounding structure, the feature points (Pb) being located, in the travel direction, rearward of the feature points (Pa) measured by the first measuring device, at a measurement time of the first measuring device, to acquire coordinates of the feature points (Pb) located rearward in the travel direction, the coordinates being expressed in a coordinate system of the second measuring device, and to use the self-location to convert the acquired coordinates into second coordinates in said external coordinate system; and an anomaly determination section that is configured to determine that anomaly occurs in the self-location estimation device if a deviation between the second coordinates and the trajectory (Pa'_tr) of the feature point group defined by the external coordinate system exceeds a threshold established to deem that the second coordinates are on the trajectory (Pa'_tr).