Quantification techniques of mineral phases in iron ore sinter has been developed by using Rietveld analysis of X-ray diffraction patterns and applied to iron ore sinters made by the sinter pot test in a laboratory. Rietveld refinements successfully determined phase fractions and structural parameters in co-existing phases such as hematite (α-Fe2O3), magnetite (Fe3O4), multi-component calcium-ferrites (SFCA: Ca2 (Ca, Fe, Al)6 (Fe, Al, Si)6O20 and SFCA-I: Ca2(Ca, Fe)3 (Ca, Fe, Al)8 (Fe, Al)8 O20) and other minor phases.It was found that strength of iron ore sinter was correlated with quantity of magnetite, and not with quantity of calcium-ferrites. And the lattice constants of calcium-ferrites were different among the specimens obtained from different positions within the sinter.Rietveld analysis was shown to be a straightforward and high-throughput technique for quantification of mineral phases in the iron ore sinter and the obtained crystallographic parameters can be used as a useful indicator to investigate the sinter reaction.