Properties of cement—such as curing time and strength—depend on the components in the clinker minerals and the ratios of the amounts of polymorphs. There are two typical polymorphs of clinker minerals, known as M1 and M3 types of alite, and cubic and orthorhombic forms of aluminate. The amount ratio of polymorphs can be evaluated easily and quickly by Rietveld refinement because the diffraction patterns vary depending on which polymorphs are present. Precise analysis is required for high-precision cement characterization. We evaluated the precise quantity of the clinker minerals by Rietveld refinement by performing ten times iterative measurements (5 min. each) using a benchtop X-ray diffractometer equipped with a high-speed 1D X-ray detector.