A navigation signal processing device includes circuitry configured to perform positioning of an antenna based on navigation signals received by the antenna from navigation satellites, set an elevation angle mask that causes inhibition of utilization of the navigation signals that are received from a specific angle range as viewed from the antenna in the positioning of the antenna, and obtain three-dimensional point cloud position data that includes data of multiple points of the surroundings as viewed from the antenna. The multiple points are obtained by a laser scanner or a stereoscopic camera and have determined three-dimensional coordinates. The circuitry is further configured to set the elevation angle mask that causes inhibition of utilization of the navigation signals that are received from a straight line direction connecting the antenna and each of the multiple points of the three-dimensional point cloud position data as viewed from the antenna.