The conventional point-counting method for modal analysis of rocks is time-consuming and depends on the user to correctly identify minerals. We introduce an alternative method using a scanning X-ray analytical microscope in conjunction with image processing and analyzing software. This method is simple and less reliant on the skill and subjectivity of the user. By using this method for thin sections or polished slabs of granitic rocks, we provide clear images showing the distribution of minerals to enable objective modal analyses to be performed quickly and efficiently.