We have developed a method for estimating the “ elasticity of input costs (labor and capital) with respect to total output” by applying the system - wide approach theory of econometrician H.Theil. It presents as a quantitative economic indicator whether the target industry is labor-intensive or capitalintensive. Analysis of the forestry and lumber/wood products industries using this method revealed that the two industries are in different structural states, with the forestry industry being labor-intensive and the lumber/wood products industry being capital-intensive. Forestry and lumber/wood products are closely related industries, and mutual understanding will promote mutual development. In positioning forestry and lumber/wood products industries as major industries in the Japanese economy, the challenge is how to respond to this unbalanced industrial structure.