NOVELTY - The reformer unit module has several hydrogen gas separation cells (4), stacked one over the other with an intermediate cylindrical supports, and mounted in an inner housing. An annular combustion chamber is formed around gas separation chamber. Steam reforming catalyst is filled in the space between stacked cells, for reforming the separated gas in separation chamber.    USE - For fuel cells used in electrically driven vehicles.    ADVANTAGE - The size of the fuel reformer is reduced by unifying the hydrogen gas separation and reforming chambers. Light weight, high sensitive fuel reformer is obtained. Contact efficiency between reforming gas and metal film is increased by the zig-zag fuel channels in separation cells.    DETAILED DESCRIPTION - The gas separation and fuel reforming chambers are unified and the separated hydrogen gas is discharged through a hydrogen permeable tube provided at bottom wall of housing. Raffinate outlets provided at bottom of housing, are connected to the combustion chamber through conduits, to burn the remaining fuel. Each cell comprises a pair of metal plates (11,11a) interposed with annular plate and porous membrane. The annular plate has fuel channels and the support layer has a central disc. The central disc has radial holes for communicating with the intermediate cylindrical supports, mounted between adjacent cells. The fuel channels in each cell are arranged in zig-zag manner and all the attachments in the cell and reformer are performed by diffusion welding. The stream reforming catalyst comprises at least one of the metals from group of Cu,Zn,Fe,Cr,Ti,Ni and at least one precious metal in the proportion of 0.01% by weight of catalyst.    An INDEPENDENT CLAIM is also included for the fuel reforming system, which includes a preheater to vaporize the liquid fuel and a fuel reformer unit. The hydrogen gas separated from reformer is supplied to anode of fuel cell.    DESCRIPTION OF DRAWING(S) - The figure shows the exploded plan view of a hydrogen gas separation cell.    Hydrogen gas separation cell (4)    Metal plates (11,11a)