Restoration of earthenware fragments is one of the important roles in archaeology area. If earthenware fragments are excavated from ruins, the fragments are restored by manual operations. When earthenware are restored with computer, the vertical direction of fragments is required. In our previous method, a set of center points derived from cross sections of fragments is estimated to determine the vertical direction. However, the vertical direction is inverted because of the displacement of center points. Therefore, to manage the vertical inversion, this paper proposes a method to accurately correct the vertical direction of earthenware fragments based on 3D measured point clouds with using linear regression.