A surveying data processing device includes a point cloud data acquiring unit, a three-dimensional model acquiring unit, a first correspondence relationship determining unit, an extended three-dimensional data generating unit, and a second correspondence relationship determining unit. The point cloud data acquiring unit acquires first point cloud data obtained by laser scanning, at a first viewpoint, and acquires second point cloud data obtained by laser scanning, at a second viewpoint. The three-dimensional model acquiring unit acquires data of a three-dimensional model. The first correspondence relationship determining unit obtains a correspondence relationship between the first point cloud data and the three-dimensional model. The extended three-dimensional data generating unit generates extended three-dimensional data in which the first point cloud data is extended, on the basis of the correspondence relationship. The second correspondence relationship determining unit determines a correspondence relationship between the extended three-dimensional data and the second point cloud data.