Magnification errors are reduced in the required range of magnification in electric charged particle beam application apparatuses and critical dimension measurement instruments. To achieve this, a first image, whose magnification for the specimen is actually measured, is recorded, a second image, whose magnification for the specimen is unknown, is recorded, and the magnification of the second image for the first image is analyzed by using image analysis. Thereby, the magnification of the second image for the specimen is actually measured. Then, magnification is actually measured in the whole range of magnification by repeating the magnification analysis described above by taking the second image as the first image. Actually measuring the magnification of images for the specimen in the whole range of magnification and calibrating the same permits a reduction of magnification errors by a digit.