To provide a device for calculating a discount rate obtained by discounting the rate of a resource consumed such as gas, electric power, city water, and a communication line in accordance with a season or the quantity of another resource consumed.

The rate calculation device is provided with a data input means 2011 for acquiring the quantity of gas consumed, a monthly degree judging means for judging whether the monthly degree of gas consumed coincides with the monthly degree of a power peak in which the quantity of power consumed is relatively increased or not, and also it is provided with a rate calculation means 2013 for calculating the discount rate of gas by referring to a specific rate table 2015 for discounting a quantitative rate corresponding to the quantity of gas consumed when the monthly degree of gas consumed coincides with the monthly degree of power peak.