In regard to a peripheral device in which commands are inputted and power is supplied from the main device, a peripheral device which can reduce power consumption while making use of a necessary function is provided. Peripheral device of the present invention comprises a functional unit which carries out a function based on commands from main device; a power control section which controls power consumption of the above-mentioned functional unit; a power profile information memory which memorizes a power profile information list that includes single or plural power profile information; and an interface section which sends and receives the above-mentioned power profile information and commands relevant to the functional unit to and from the above-mentioned main device; wherein the above-mentioned interface section corresponds to the demand from the above-mentioned main device and sends the above-mentioned power profile information list to the above-mentioned main device; and the above-mentioned power control section controls power consumption of the above-mentioned functional unit by corresponding to the selected information of the above-mentioned power profile information that was received from the above-mentioned
main device.