To provide a fuel reforming device capable of improving total fuel consumption in a case when a reformed gas is supplied in operation of an internal combustion engine.

A reforming fuel injection amount control part provided on an ECU 60 performs a supply amount limitation control to be the control for decrease the injection amount of the reforming fuel when a reforming fuel remaining amount to be the fuel for generating the reformed gas is not larger than the predetermined amount of Qfuel. Therefore, the reforming fuel hardly runs down, and even when the reforming fuel remaining amount becomes a little, the reforming fuel can be suppressed from being run out before the main fuel to be the fuel used in the operation of the engine. The reformed gas is generated in the operation of the engine over a long time thereby, the reformed gas can be continued to supply into the engine 1 as required, and therefore a reforming effect by supplying the reformed gas into the engine 1 can be maintained. In the result, the total fuel consumption in the case when the reformed gas is supplied in the operation of the engine 1 can be improved.