A power over fiber system includes: a power sourcing equipment, a powered device, an optical fiber cable, a temperature sensor and a controller. The power sourcing equipment includes a semiconductor laser that oscillates with electric power, thereby outputting 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 temperature sensor detects a temperature of the photoelectric conversion element. The controller performs a process of lowering an output level of the feed light in response to the temperature detected by the temperature sensor being equal to or higher than a predetermined threshold value, and performs a process of raising the output level of the feed light in response to the temperature being lower than the predetermined threshold value.