A method was proposed for the estimation of ground surface elevation in forested hills and mountains using helicopter-borne laser scanner data. In the process of deriving ground surface by the subtraction of tree heights from canopy surface, we considered the spatial distribution of tree heights. Tree heights varied with the topographic variable: horizontal distance from stream, and a logistic curve were applied in the regression analysis. The validation with field-surveyed elevation data indicated that our method showed better estimation than the method of using mean tree height.