A power-over-fiber system includes a power sourcing equipment, a powered device, and an optical fiber cable. The power sourcing equipment includes a semiconductor laser that oscillates with electric power to output feed light. The powered device includes a photoelectric conversion element that converts the feed light from the power sourcing equipment into electric power. The optical fiber cable transmits the feed light from the power sourcing equipment to the powered device. The power-over-fiber system includes a temperature sensor that detects a temperature in the power sourcing equipment. When the temperature detected by the temperature sensor is equal to or higher than a predetermined threshold, a process of decreasing electric power input to the semiconductor laser is performed. When the temperature detected by the temperature sensor is lower than the predetermined threshold, a process of increasing electric power input to the semiconductor laser is performed.