A smart plug socket device comprising: a lower housing that has a pair of through-holes on a bottom surface thereof; an AC/DC conversion board unit comprising a pair of plug pins that pass through the pair of through-holes of the lower housing, a transformer that receives AC power through the pair of plug pins and converts the AC power to DC power, a power connector for delivery of the DC power, and a pair of power lines that receive the AC power through the pair of plug pins; a relay board unit that is stacked on the AC/DC conversion board unit comprising a relay module that receives the AC power through the pair of power lines and supply or interrupt the AC power to or from a pair of connection terminals in response to a control command from a controller module, a power connector that is electrically and mechanically connected to the power connector of the AC/DC conversion board unit, a power/signal connector for delivering the DC power and exchanging signals with a controller module, and the pair of connection terminals into which plug pins of an electronic device are inserted; a controller board unit that is stacked on the relay board unit comprising a controller board that has through-holes, through which the pair of connection terminals pass, the controller module that is coupled to the controller board and control an operation of the smart plug socket device and wirelessly communicate with an external device, and a power/signal connector that is coupled to the controller board and is electrically and mechanically connected with the power/signal connector of the relay board unit; and an upper housing that is coupled to the lower housing to define a space between the upper housing and the lower housing and has a pair of insertion holes, through which the plug pins of the electronic device are inserted, on a bottom surface thereof, characterized by further comprising: a board cover unit that is stacked on the relay board unit between the relay board unit and the controller board unit comprising a board cover that has a hole for exposing the power/signal connector of the relay board unit, and a pair of terminal covers that are formed on the board cover and expose the pair of connection terminals of the relay board unit and surround a circumference of the pair of connection terminals. a lower housing that has a pair of through-holes on a bottom surface thereof; an AC/DC conversion board unit comprising a pair of plug pins that pass through the pair of through-holes of the lower housing, a transformer that receives AC power through the pair of plug pins and converts the AC power to DC power, a power connector for delivery of the DC power, and a pair of power lines that receive the AC power through the pair of plug pins; a relay board unit that is stacked on the AC/DC conversion board unit comprising a relay module that receives the AC power through the pair of power lines and supply or interrupt the AC power to or from a pair of connection terminals in response to a control command from a controller module, a power connector that is electrically and mechanically connected to the power connector of the AC/DC conversion board unit, a power/signal connector for delivering the DC power and exchanging signals with a controller module, and the pair of connection terminals into which plug pins of an electronic device are inserted; a controller board unit that is stacked on the relay board unit comprising a controller board that has through-holes, through which the pair of connection terminals pass, the controller module that is coupled to the controller board and control an operation of the smart plug socket device and wirelessly communicate with an external device, and a power/signal connector that is coupled to the controller board and is electrically and mechanically connected with the power/signal connector of the relay board unit; and an upper housing that is coupled to the lower housing to define a space between the upper housing and the lower housing and has a pair of insertion holes, through which the plug pins of the electronic device are inserted, on a bottom surface thereof, characterized by further comprising: a board cover unit that is stacked on the relay board unit between the relay board unit and the controller board unit comprising a board cover that has a hole for exposing the power/signal connector of the relay board unit, and a pair of terminal covers that are formed on the board cover and expose the pair of connection terminals of the relay board unit and surround a circumference of the pair of connection terminals.