A smart device is discussed, which is connected to a smart grid to perform a power saving function. According to an embodiment, the smart device includes a power information receiving unit configured to receive power information through the smart grid network; a power saving control unit configured to perform the power saving function for at least one apparatus based on the power information in a power saving mode; at least one mode switching unit configured to switch from the power saving mode to a manual mode according to a user command; and a manual mode operational time determining unit configured to determine a manual mode operational time for operating the at least one apparatus in the manual mode, the at least one mode switching unit further configured to switch from the manual mode back to the power saving mode, automatically, when the manual mode operational time expires.