Respective targets 10 are set at a plurality of reference points S1 to S16 provided on a construction. 3D measuring instrument 18 is firstly installed at a central site O of the first polygon G1 that has apexes at three or more of the reference points S, and measures 3D coordinates of the reference points in the first polygon G1 in a predetermined coordinate system, from 3D vectors for the apexes of the first polygon G1 which are collimated by the 3D measuring instrument 18. The 3D measuring instrument 16 is then moved to a central site P(n) of an n-th polygon G(n) (n being an integer of 2 or more) that has apexes at three or more of the reference points whose coordinates have been measured and one or more of the reference points whose coordinates have not been measured, and measures 3D coordinates of the post-movement location P(n) of the measuring instrument 18 and the reference points in the n-th polygon G(n) whose coordinates have not been measured in the predetermined coordinate system, from 3D vectors for the apexes of the n-th polygon G(n) which are collimated by the measuring instrument 18. After measuring 3D coordinates of all the reference points on the construction by repeating a cycle from the step of moving the 3D measuring instrument 18 to the central site of the n-th polygon G(n) to the step of measuring 3D coordinates of the reference points in the n-th polygon G(n) whose coordinates have not been measured, 3D coordinates of each reference point S are determined through network-adjustment calculation.