A method of generating an elemental map includes: acquiring a plurality of correction channel images by scanning a surface of a standard specimen having a uniform elemental concentration with a primary beam and generating a correction channel image for each channel; generating correction information for each pixel of each correction channel image among the plurality of correction channel images based on a brightness value of the pixel; acquiring a plurality of analysis channel images by scanning a surface of a specimen to be analyzed with the primary beam and generating an analysis channel image for each channel; correcting brightness values of pixels constituting an analysis channel image among the plurality of analysis channel images based on the correction information; and generating an elemental map of the specimen to be analyzed based on the plurality of analysis channel images having pixels with corrected brightness values.