The authors examined the factors of bed soil affecting the loss of surface soil and the effects of these factors on the extent of the soil loss. They conducted a multivariate analysis using actual measurement value at a laboratory erosion experiment. They also conducted a simulation of erosion in soil loss using the bed soil factors. Soil loss quantity is dependent on the coefficient of permeability of bed soil; the steeper the latter is, the more the former increases. Lateral soil scattering quantity is not much affected with the permeability of bed soil, nor with the gradient of a slope. When the slope gradient of bed soil is equal, soil loss quantity is affected with the coefficient of permeability and the ignition loss of the bed soil. On the otherhand , when the slope gradient of bed soil is different, soil loss quantity is most affected with the slope gradient, followed by the coefficient of permeability of the bed soil
