To provide a bridge shape measuring method whereby the shape of even a large bridge can be measured easily.

Measuring apparatuses 10, 12 for measuring the three- dimensional positions of targets 20 are placed, respectively, at the right and left of a bridge. The three-dimensional position of a common target placed at an immobile point 18 is measured by the right and left measuring apparatuses 10, 12, and the three-dimensional position of each of the targets 20 mounted on the parts to be measured of the bridge is measured by the right and left measuring apparatuses 10, 12. The measured three-dimensional position of each part to be measured is corrected by means of the three-dimensional position of the immobile point 18 to measure the three-dimensional shape of the bridge. Further, the three-dimensional positions corrected are interpolated to calculate the shape between the parts to be measured.