NOVELTY - The container has a base (1) with a cavity in which a fuel modifier (9) which generates reformed gas containing hydrogen gas from a fuel, is accommodated, and a cover (4) which covers the cavity on the upper surface of the base. A discharge pipe (5b) is connected to the exterior in the cavity for emitting the reformed gas from the fuel modifier. Slender protrusions (A) are formed in the inner surface of the base, outer surface of the base, inner surface of the cover, and/or outer surface of the cover.    USE - For accommodating fuel modifier in fuel reformer (claimed) used in fuel cell systems.    ADVANTAGE - The container is lightweight. Since the protrusion effectively distributes the heat radiated from the fuel modifier and transmitted to the base or cover, the local increase in temperature is prevented. As a result, destruction of another component in a portable apparatus is prevented effectively, and the fuel cell system is used stably and safely over a long period of time. The deformation of the base and the cover towards the inside direction of the cavity is prevented when the container is in vacuum state. The base and cover are reinforced by the protrusion. Since the base and cover are not thermally distorted, air tightness of the container is maintained. Since the protrusions are formed in the vertical and horizontal directions, the anisotropy in bending strength of the base and cover is prevented.    DETAILED DESCRIPTION - The container has a base (1) with a cavity in which a fuel modifier (9) which generates reformed gas containing hydrogen gas from a fuel, is accommodated, and a cover (4) which covers the cavity on the upper surface of the base. A discharge pipe (5b) is connected to the exterior in the cavity for emitting the reformed gas from the fuel modifier. A supply pipe (5a) is connected to the exterior in the cavity for supplying fuel to the fuel modifier. Slender protrusions (A) are formed in the inner surface of the base, outer surface of the base, inner surface of the cover, and/or outer surface of the cover. An INDEPENDENT CLAIM is included for fuel reformer (11).    DESCRIPTION OF DRAWING(S) - The figure shows the perspective diagram of a fuel reformer.    Base (1)    Cover (4)    Supply pipe (5a)    Discharge pipe (5b)    Fuel modifier (9)    Fuel reformer (11)    Protrusions (A)