Fuel reforming system

A fuel cell power plant comprises a fuel reforming system (1). The fuel reforming system (1) comprises a vaporizer (7) which vaporizes liquid fuel and supplies fuel vapor to a reformer (9). The vaporizer (7) heats injected fuel so as to vaporize it by a heating elements, and supplies it to the reformer (9) via a fuel vapor supply passage (32) comprising a first valve (17). In a standby mode of the vaporizer (7) when the first valve (17) is closed, surplus fuel and heat energy in the standby state are recovered by providing a recovery passage (19) which recovers fuel in the vicinity of the heating elements to the fuel tank (6) without allowing it to flowing into the vapor supply passage (32).