Fuel synthesis system

Provided is a fuel synthesis system which, when power is stopped or insufficient, can quickly compensate for the shortage of power, thereby preventing the system from stopping or safely stopping the system. The fuel synthesis system is provided with: a supply means (11) for supplying carbon dioxide and a supply means (12) for supplying hydrogen, the supply means (11) and the supply means (12) being disposed upstream of the main passage; a catalyst reactor (6) which is disposed downstream of the supply mechanism and which synthesizes fuel using a fuel synthesis catalyst; a first power supply device that normally supplies power based on renewable energy; a second power supply device (14) that supplies power by means of the fuel cell; the fuel synthesis system is characterized by being provided with a power control means that, when the power supplied by the first power supply device is reduced, generates power by supplying hydrogen to the second power supply device by means of the hydrogen supply means, and cont