[en] Underground buried hazardous substances may migrate to the surface soil to cause a pollution problem mainly due to capillary phenomena. A possibility to suppress upward vertical migration of water and mass by the use of coarse grain soil as capillary barrier was studied experimentally. Control effect of the insertion of coarse sand layer on upward water and mass migration was studied with one-dimentional column experiments, which showed retardation of the upward migration of water and chloride ion. The particle radius of soil cover and the control layer effective for control of mass migration was searched and the influence of rainfall was examined. The advantage and disadvantage capillary barrier as water barrier was discussed in comparison with other methods. The capillary barrier cannot be used independently, but, may be used as a component of multiple control to enhance the reliability of the disposal sites. (T.H.)