This paper proposed the calculation method of the avoided cost for natural gas and district heating DSM programs. And the proposed method is applied to real DSM programs. The avoided cost for natural gas consists of commodity avoided cost, supply equipment avoided cost, storage equipment avoided cost, and electric power avoided cost. In case of the district heating, avoided cost consists of heat generation equipment avoided cost, heat energy avoided cost, environment avoided cost, and electric power avoided cost. This method can be used to evaluate the benefit of DSM programs quantitatively in cost. Therefore, this method can contribute to make the cost-effectiveness evaluation system and to operate the DSM programs for natural gas and district heating effectively.