A fuel reforming method includes the step of supplying carbon-containing fuel and steam to a reactor filled with a fuel reforming catalyst and a CO.sub.2 absorbent and discharging CO.sub.2, and setting the absorbent at an absorption temperature, thereby converting the carbon-containing fuel into reformed fuel, and separating CO.sub.2 from the reformed fuel, the step of obtaining a product gas by oxidizing a portion of the reformed fuel and/or the carbon-containing fuel with an oxidizer, and heating the absorbent with this product gas to a regeneration temperature, thereby regenerating the absorbent and storing heat in this absorbent, and the step of supplying the carbon-containing fuel and steam to the reactor, thereby cooling, to the absorption temperature, the absorbent heated to the regeneration temperature, and converting the carbon-containing fuel into reformed fuel by heat energy stored in the CO.sub.2 absorbent. An apparatus for the method is also disclosed.