A method of manufacturing a reflective mask blank, the mask blank comprising a substrate, a multilayer reflection film for EUV light reflection, a protection film, and an absorber film for EUV light absorption formed on one main surface of the substrate, in that order from the substrate side, and a conductive film formed on the other main surface of the substrate, the method comprising the steps of: forming the conductive film on said other main surface, forming a coordinate reference mark on said other main surface side, forming the multilayer reflection film and protection film on said one main surface, measuring the flatness of the substrate by measuring a warpage or deflection of the substrate by a function for adjusting the focus of an optical system used for detection of the coordinate reference mark, inspecting for defects in the multilayer reflection film and protection film formed in step, obtaining positional information of a detected defect on the basis of coordinates defined with reference to the coordinate reference mark, correcting the position of the defect based on the determined warpage or deflection, and saving the positional information into a recording medium, after step, forming the absorber film on the protection film, measuring the flatness of the substrate by the method in step, and inspecting for defects in the absorber film formed in step, obtaining positional information of a detected defect on the basis of coordinates defined with reference to the coordinate reference mark, correcting the position of the defect based on the determined warpage or deflection in step, and saving the positional information into a recording medium. a substrate, a multilayer reflection film for EUV light reflection, a protection film, and an absorber film for EUV light absorption formed on one main surface of the substrate, in that order from the substrate side, and a conductive film formed on the other main surface of the substrate, the method comprising the steps of: forming the conductive film on said other main surface, forming a coordinate reference mark on said other main surface side, forming the multilayer reflection film and protection film on said one main surface, measuring the flatness of the substrate by measuring a warpage or deflection of the substrate by a function for adjusting the focus of an optical system used for detection of the coordinate reference mark, inspecting for defects in the multilayer reflection film and protection film formed in step, obtaining positional information of a detected defect on the basis of coordinates defined with reference to the coordinate reference mark, correcting the position of the defect based on the determined warpage or deflection, and saving the positional information into a recording medium, after step, forming the absorber film on the protection film, measuring the flatness of the substrate by the method in step, and inspecting for defects in the absorber film formed in step, obtaining positional information of a detected defect on the basis of coordinates defined with reference to the coordinate reference mark, correcting the position of the defect based on the determined warpage or deflection in step, and saving the positional information into a recording medium. forming the conductive film on said other main surface, forming a coordinate reference mark on said other main surface side, forming the multilayer reflection film and protection film on said one main surface, measuring the flatness of the substrate by measuring a warpage or deflection of the substrate by a function for adjusting the focus of an optical system used for detection of the coordinate reference mark, inspecting for defects in the multilayer reflection film and protection film formed in step, obtaining positional information of a detected defect on the basis of coordinates defined with reference to the coordinate reference mark, correcting the position of the defect based on the determined warpage or deflection, and saving the positional information into a recording medium, after step, forming the absorber film on the protection film, measuring the flatness of the substrate by the method in step, and inspecting for defects in the absorber film formed in step, obtaining positional information of a detected defect on the basis of coordinates defined with reference to the coordinate reference mark, correcting the position of the defect based on the determined warpage or deflection in step, and saving the positional information into a recording medium.