NOVELTY - Reformer for producing reformed gas from fuel gas and water vapor, has a reformed-gas generation flow path and a combustion gas flow path. Reformed-gas generation flow path has (1) a reforming-catalyst part, (2) a shift catalyst part and (3) a CO selective oxidation-catalyst part which was going downstream along the flow direction in the upstream direction of the reformed gas.    USE - Used for producing a reformed gas for use in e.g. fuel electrical generation systems.    ADVANTAGE - The reformer is of a miniature size and has a simple structure. The device is highly efficient and has excellent starting characteristics.    DETAILED DESCRIPTION - Reformer for producing reformed gas from fuel gas and water vapor, has a reformed-gas generation flow path and a combustion gas flow path. Reformed-gas generation flow path has:    (1) a reforming-catalyst part;    (2) a shift catalyst part; and    (3) a CO selective oxidation-catalyst part which was going downstream along the flow direction in the upstream direction of the reformed gas.    A reformed-gas generation flow path has:    (a) a 1st flow path which adjoins a combustion gas flow path, and has a modification-catalyst part; and    (b) a 2nd flow path adjacent to a 1st flow path.    A 2nd flow path has a 1st heat-recovery part adjacent to a modification-catalyst part. A 1st flow path has a 2nd heat-recovery part adjacent at least 1 of a shift catalyst part, and the reformed gas and CO selective oxidation-catalyst part on the upstream side of the flow of reformed gas from a modification-catalyst part.    DESCRIPTION OF DRAWING(S) - Figure 1 shows an example of the device.    Reforming gas generation flow path (1)    First flow path (1a)    Second flow path (1b)    Reformed catalyst part (2)    Shift catalyst part (3)    CO selective oxidation catalyst part (4)    Combustion gas flow path (5)    Second heat recovery part (6)    First heat recovery part (7)    Combustion gas introduction flow path (9)    Incombustible cylinder (10)    Steam generator (13)    Gas mixing chamber (30)    Air supply port (33)    Third heat recovery part (38)    Linking part (80)    Cover plate (81)    Exhaust opening (82)    Burner (83)    Mixing chamber (84)    Combustion chamber (85)    Outer cylinder (100)    Inner cylinder (102)    Wall (104)    Plate (106)    Inner tube end (108)    Welded part (109)    Outer tube end (110)    Welded part (114)