A self-position estimation device comprising: a self-position estimation portion configured to estimate a self-location and attitude on a high-precision map from measurement results of a sensor to measure objects around a vehicle; a feature detection portion configured to detect objects from the measurement results of the sensor and to save a detection result in past feature data; a low-precision section detection portion configured to detect a low-precision section indicating low estimation accuracy based on the self-location and attitude estimated by the self-position estimation portion, wherein the low-precision section detection portion is configured to detect, when a positional change greater than or equal to a predetermined threshold value at times immediately following each other is found in a self-location and attitude on the high-precision map estimated by the self-position estimation portion, a section before a point corresponding to the positional change as a low-precision section; a self-map generation portion configured to generate a self-generated map saving the position of a detected object in the coordinate system of the high-precision map and the type of the object only in the low-precision section detected by the low-precision section detection portion, further comprising: a feature matching portion configured to provide matching between an object detected by the feature detection portion and an object included in the self-generated map, wherein the self-position estimation portion is further configured to estimate a self-location and attitude based on a measurement result of the sensor and a matching result of the feature provided by the feature matching portion; and wherein the self-map generation portion is configured to estimate a past self-location and attitude in the low-precision section and to generate the self-generated map based on the estimated past self-location and attitude estimated by the self-position estimation portion and the past feature data. a self-position estimation portion configured to estimate a self-location and attitude on a high-precision map from measurement results of a sensor to measure objects around a vehicle; a feature detection portion configured to detect objects from the measurement results of the sensor and to save a detection result in past feature data; a low-precision section detection portion configured to detect a low-precision section indicating low estimation accuracy based on the self-location and attitude estimated by the self-position estimation portion, wherein the low-precision section detection portion is configured to detect, when a positional change greater than or equal to a predetermined threshold value at times immediately following each other is found in a self-location and attitude on the high-precision map estimated by the self-position estimation portion, a section before a point corresponding to the positional change as a low-precision section; a self-map generation portion configured to generate a self-generated map saving the position of a detected object in the coordinate system of the high-precision map and the type of the object only in the low-precision section detected by the low-precision section detection portion, further comprising: a feature matching portion configured to provide matching between an object detected by the feature detection portion and an object included in the self-generated map, wherein the self-position estimation portion is further configured to estimate a self-location and attitude based on a measurement result of the sensor and a matching result of the feature provided by the feature matching portion; and wherein the self-map generation portion is configured to estimate a past self-location and attitude in the low-precision section and to generate the self-generated map based on the estimated past self-location and attitude estimated by the self-position estimation portion and the past feature data. a feature matching portion configured to provide matching between an object detected by the feature detection portion and an object included in the self-generated map, wherein the self-position estimation portion is further configured to estimate a self-location and attitude based on a measurement result of the sensor and a matching result of the feature provided by the feature matching portion; and wherein the self-map generation portion is configured to estimate a past self-location and attitude in the low-precision section and to generate the self-generated map based on the estimated past self-location and attitude estimated by the self-position estimation portion and the past feature data.