In a substrate processing control method, a first process acquires a first-reflectance-spectrum of a beam reflected from the first-fine-structure and a second-reflectance-spectrum of a beam reflected from the second-fine-structure for each of varying-pattern-dimensions of the first-fine-structure when the pattern-dimension of the first-fine-structure is varied. A second process acquires reference-spectrum-data for each of the varying-pattern-dimensions of the first-fine-structure by overlapping the first-reflectance-spectrum with the second-reflectance-spectrum. A third process actually measures beams reflected from the first and the second-fine-structure, respectively, after irradiating light beam on to the substrate and acquiring reflectance-spectrums of the actual-measured beams as actual-measured spectrum data. A fourth process compares the actual-measured spectrum data with the respective reference-spectrum data and acquiring, as the measured pattern-dimension, one of the varying-pattern-dimensions corresponding to reference-spectrum data that is closely matches with the actual-measured spectrum data. A final process ends the processing of the substrate if the measured pattern-dimension reaches a value.