A fuel reforming system that is applied to an engine and configured to reform fuel to be supplied to an engine body, wherein the engine includes the engine body, an intake passage through which intake air to be introduced into the engine body flows and an exhaust passage through which exhaust gas exhausted from the engine body flows, the fuel reforming system comprising: an EGR passage configured to connect the intake passage and the exhaust passage; a fuel injection device (32, 34) capable of injecting fuel into the EGR passage; a reforming catalyst provided in the EGR passage and capable of reforming the fuel injected from the fuel injection device (32, 34); an oxidation catalyst provided in the EGR passage; an air supply device (25, 31) configured to supply air to the EGR passage; a temperature detector configured to detect a temperature of the reforming catalyst; a determiner configured to determine whether clogging in an interior of the reforming catalyst is present or is occurring; and a controller configured to control the fuel injection device (32, 34) and the air supply device (25, 31), wherein when it is determined by the determiner that the clogging in the reforming catalyst is present, and the temperature of the reforming catalyst detected by the temperature detector is less than a predetermined first temperature, the controller is configured to execute first catalyst regeneration control for driving the air supply device (25, 31) so that the air is supplied to the EGR passage, and causing the fuel injection device (32, 34) to inject the fuel so that the fuel injected from the fuel injection device (32, 34) is introduced into the reforming catalyst together with the air, and when it is determined by the determiner that the clogging in the reforming catalyst is present, and the temperature of the reforming catalyst is equal to or more than the first temperature, the controller is configured to execute second catalyst regeneration control for driving the air supply device (25, 31) so that the air is supplied to the EGR passage, and stopping fuel injection of the fuel injection device (32, 34). an EGR passage configured to connect the intake passage and the exhaust passage; a fuel injection device (32, 34) capable of injecting fuel into the EGR passage; a reforming catalyst provided in the EGR passage and capable of reforming the fuel injected from the fuel injection device (32, 34); an oxidation catalyst provided in the EGR passage; an air supply device (25, 31) configured to supply air to the EGR passage; a temperature detector configured to detect a temperature of the reforming catalyst; a determiner configured to determine whether clogging in an interior of the reforming catalyst is present or is occurring; and a controller configured to control the fuel injection device (32, 34) and the air supply device (25, 31), wherein when it is determined by the determiner that the clogging in the reforming catalyst is present, and the temperature of the reforming catalyst detected by the temperature detector is less than a predetermined first temperature, the controller is configured to execute first catalyst regeneration control for driving the air supply device (25, 31) so that the air is supplied to the EGR passage, and causing the fuel injection device (32, 34) to inject the fuel so that the fuel injected from the fuel injection device (32, 34) is introduced into the reforming catalyst together with the air, and when it is determined by the determiner that the clogging in the reforming catalyst is present, and the temperature of the reforming catalyst is equal to or more than the first temperature, the controller is configured to execute second catalyst regeneration control for driving the air supply device (25, 31) so that the air is supplied to the EGR passage, and stopping fuel injection of the fuel injection device (32, 34).