Al-27 multiple quantum magic-angle spinning (MQMAS) spectroscopy at high magnetic field (16.4 T) was applied for the first time to the structural analysis of inorganic matter in natural coals. Resolution of 3QMAS spectra at 7.0 T was insufficient for identification of the inorganic matter in natural coals, because of incomplete cancellation of the second-order quadrupolar effects, although 3QMAS spectra gave better resolution than conventional magic-angle spinning (MAS) spectra. On the other hand, an increased magnetic field (16.4 T) greatly improved 3QMAS spectral resolution, compared to that obtained at 7.0 T; hence, it facilitated the assignment of some minerals. Moreover, 3QMAS spectra recorded at 16.4 T led to signal enhancement by a factor of similar to4, compared to spectra taken at 7.0 T. Higher field strengths became useful for the analysis of inorganic matter in natural coals that have a low concentration of aluminum (similar to2.0 mass %). 3QMAS and 5QMAS spectra at 16.4 T were also compared. As far as inorganic matter in natural coals is concerned, the spectral resolution was almost unchanged between 3QMAS and 5QMAS, although the excitation of 5 quantum coherences is less efficient than that for 3 quantum coherences. It is concluded that the combination of MQMAS techniques with high magnetic field is a very effective for characterization of inorganic matter in natural coals and is especially well-suited to the analysis of clay minerals that have low crystallinity.