A technique for preventing decrease in positioning precision due to reflected waves from a navigation satellite that is blocked by an obstacle in a positioning technique using a GNSS is provided. A navigation signal processing device includes a data obtaining unit 121, an elevation angle mask setting unit 125, and a point cloud position data obtaining unit 123. The data obtaining unit 121 performs positioning based on navigation signals from navigation satellites. The elevation angle mask setting unit 125 sets a condition for restricting utilization of the navigation signals from a specific navigation satellite. The point cloud position data obtaining unit 123 obtains three-dimensional point cloud position data of the surroundings of an antenna that receives the navigation signals. The elevation angle mask setting unit 125 sets the condition based on the three-dimensional point cloud position data.