A wired-rope measuring device, provided with two cameras 1, 2 that shoot one or no less than two wired ropes 8 from different directions and an analyzing device 5 that analyzes image data that is an image shot by the two cameras 1, 2, wherein the analyzing device 5 applies the principle of triangulation by a stereo method to the image data to seek a center coordinate P0 of the wired rope 8 relative to the cameras 1, 2 and volumetric anamorphosis is corrected when calculating a diameter D of the wired rope 8 based on the center coordinate P0 of the wired rope 8.