Provided is a control device that makes it possible to surely give an appropriate instruction to operate. An appliance control device that controls an electric appliance that performs one of a first operation and a second operation includes: a price obtaining unit that obtains information indicating a price of power; a detecting unit that detects a change in the price in a not shorter one of the first period and the second period, the price being indicated in the obtained information; a first calculating unit that calculates a first cost produced when the electric appliance performs the first operation, in the case where the change is detected; a second calculating unit that calculates a second cost produced when the electric appliance performs the second operation, in the case where the change is detected; a comparing unit; and an instructing unit that instructs performing of a determined operation.