Abstract: The concept on geological disposal of high level radioactive waste (H LW) is a multi-barrier sysytem, including waste container, buffer/backfill mate rial and geological formation. Some significant mineralogical problems related t o geological disposal of HLW are shown below: 1.Mineralogical study of montmoril lonite in bentonite is very important in study on buffer/backfill material of HL W repository. Bentonite mainly consisting of Na-montmorillonite and that of Ca -montmorillonite are very different in many properties. What kind of bentonite is better as a buffer/backfill material in HLW repository? 2.Sorption capacity o f 99　Tc and 129　I on stibnite, boulaugerite and tiemannite is very good. However, these minerals are rare in the nature. It is necessary for miner alogists to find substitutes of those minerals as additives in buffer/backfill m aterials of HLW repository. 3.Zeolite has a good sorption capac ity for some nuclides. Mineralogists should pay attention to application of zeol ite in geological disposal of nuclear wastes.