Most home electric appliances have standby energy waste when they are at idle mode. This standby energy is about 3% to 11% of total household electricity consumption. For several millions of households in Taiwan, this standby energy would cause billion dollars of waste per year. Therefore, in this paper we propose a standby-energy-saving socket using a microcontroller unit (MCU) to reduce the standby-energy waste. The user can start up this standby-energy-saving socket to supply power to appliances through the appliances infrared remote control or the button on the socket. When the appliances enter into the standby mode, the current sensor in the socket automatically detects it and the MCU turns off the power through a relay to reduce the standby power to zero. Based on the test, the MCU in the proposed standby-energy-saving socket only consumes about 3 mW when the socket is at sleep mode, 6 mW at working mode. The cost of this proposed socket is $9. The standby-energy saving tested on a PC is reduced by 99.93%.