The Kuraishi and Kubino landslide area in the central Tokushima prefacture belong to the sambagawa crystalline schist zone which is formed of green schist and black schist. The X-ray diffraction method was used to examine the minerals contained in the clay which was collected from these two areas. The results were as follows; 1) The weathered rocks in the clay collected from the Kubino area contained sericite and kaolinite as main clay minerals. But 14 Å minerals were not found. Montmorillonite was in the debris. 2) Montmorillonite existed at another place. The place was in two border between green schist and black schist which was in the slope vertical to the road, north of the Kubino area. 3) At the Kuraishi landslide area two clay samples were gathered. One was surface clay which contained sericite and kaolinite, and the other was fault clay with montmorillonite in it.