A fuel reformer which converts a raw material to a reformed gas composed of H2 by steam reforming consists of: (a) a combustion section where a heat source gas is generated; (b) a gasification section where the raw material is heated and gasified into the raw material gas with the heat source gas from the combustion section; (c) a reforming and conversion section where the raw material gas from the gasification section is converted to a reformed gas principally composed of H2 with a reforming catalyst heated with the heat source gas from the combustion section and at the same time the concn. of CO in the reformed gas is decreased; and (d) an oxidn. and removal section where the concn. of the remaining CO from the reforming and conversion section is decreased with an oxidn. catalyst selective to CO. The gasification section consists of alternate layers of a gasification layer through which the raw material is passed and a heating layer through which the heat source gas from the combustion section is passed to heat the raw material in the gasification layers. The reforming and conversion section contains a reforming catalyst and consists of alternate layers of a reforming catalyst layer through which the raw material gas from the gasification layer of the gasification section is passed and a heating layer through which the heat source gas from the heating layer of the gasification section is passed to heat the reforming catalyst in the reforming catalyst layers. The oxidn. and removal section contains an oxidn. catalyst selective to CO and consists of alternate layers of an oxidn. catalyst layer through which the reformed gas from the reforming and conversion section is passed and a heating layer through which the heat source gas from the heating layer of the reforming and conversion section is passed to heat the oxidn. catalyst in the oxidation catalyst layers. The combustion, gasification, reforming and conversion, and oxidation and removal sections are connected integrally.    USE/ADVANTAGE -   The fuel reformer can be used to reform fossil fuels such as methanol and LNG to obtain reformed gas principally composed of H2 which can be used as a fuel of fuel cells. The fuel reformer is small in size and the concn. of CO in the reformed gas can be lowered.