An increase in the price of imported fossil fuels indirectly increases the producer price in non-energy sectors; however, this indirect influence cannot be taken into account by the traditional portfolio approach. This study proposes an analytical framework combining the input-output (I-O) model and the portfolio approach that can take the indirect influence into account. A risk of an increase in the producer price in Japanese non-energy sectors during the period 1970-2000 is estimated, and the causes of a decrease in the risk through the analysis period are clarified by decomposing an index of the risk. The result indicates that almost all non-energy sectors have decreased this risk during the analysis period. The degree and cause of the decrease depends on a sector's location in the hierarchical structure of Japanese industries. For example, assembly sectors have decreased their risk mainly as the result of improvement in energy usage by upstream sectors, such as material sectors, rather than their own improvements. Proper policies considering such a structure are required to decrease the risk further because the effort taken to do so is seldom motivated by economic profit. (C) 2010 Elsevier Ltd. All rights reserved.