A fiber-producing apparatus includes a storage tank for storing a melt of a source material, an electric storage tank heater, a non-contact thermometer for the melt, a temperature control section which between the electric heater and its power supply, which controls the electric heater based on measurement results obtained from the non-contact thermometer to adjust the temperature of the melt, a nozzle for ejecting the melt in the storage tank, a collector for collecting a fiber, a voltage generator for electrifying the melt, and an insulating transformer disposed between the temperature control section and the electric heater. Since a closed circuit is formed by the electric heater, the electric heater power supply, the temperature control section, and the insulating transformer disposed therebetween, no high-voltage current flows into the electric heater power supply or the temperature control section. This allows stable spinning to be readily performed without breaking the apparatus.