An electric refrigerator is provided with a casing formed of a heat-insulating layer and defining an opening; a heat-insulating door for openably closing the opening of the casing; a thermal conductor arranged in the casing and provided with a heat-conducting surface located opposite an interior space in the casing; a Peltier device thermally connected with the thermal conductor; and a device power supply for feeding electric power to the Peltier device. The electric refrigerator is also provided with a control unit for controlling the device power supply so that, after the heat-insulating door is closed subsequent to opening thereof, the device power supply supplies the Peltier device with electric power controlled in a range of from 1.3 to 2 times as much rated electric power required to maintain a preset interior temperature of the casing.