An electronic device may include an embedded storage device connected to directly communicate with an extended storage device, and an application processor connected to directly communicate with the embedded storage device and connected to the extended storage device through the embedded storage device. The embedded storage device includes a monitoring device that monitors commands received from the application processor. The monitoring device generates a command state signal representing a state of the embedded storage device and the extended storage device based on a result of monitoring the commands. The embedded storage device operates so that a power supply is controlled in a part or all of the embedded storage device according to the command state signal.