STRAIN MEASURING METHOD AND STRAIN MEASURING SYSTEM

PROBLEM TO BE SOLVED: To provide a strain measuring method and strain measuring system capable of improving the measuring accuracy of strain by accurately image-recognizing a mark put on a surface of a measuring object.SOLUTION: The strain measuring method includes: imaging processes S13 and S14 of acquiring a first image and second image of a surface before and after deformation of a measuring object; an average deformation ratio calculation process S15 of calculating an average deformation ratio of the measuring object on the basis of the first image before the deformation and the second image after the deformation; a first correction process S16 of contracting or enlarging the second image using the inverse of the average deformation ratio as the scale ratio and acquiring a correction image of the second image; a strain calculation process S17 of identifying, from the correction image, by image recognition, the position indicating the highest correlation with each of a plurality of areas into which the first image is divided and calculating the moving amount of each area to calculate strain of the measuring object; and a second correction process S18 of correcting the strain by multiplying the strain of the measuring object calculated in the strain calculation process by the average deformation ratio.