NOVELTY - A modification-reaction apparatus (10) includes a catalyst layer (21) including catalyst (20), and equipped with a water vapor flow path (24) and a raw-materials-and-mineral-fuel flow path (26). The catalyst layer has a surface (A) (21a,22a) and a surface (B) (21b,22b). The catalyst accelerates the modification reaction between hydrocarbon-type raw material, mineral fuel and water vapor in reaction apparatus and generates gas-containing hydrogen. The water-vapor flow path and raw-materials-and-mineral-fuel flow path positioned along surfaces (A and B) respectively.    USE - Modification-reaction apparatus is used for fuel cell power generating device (claimed) used for manufacturing fuel gas-containing hydrogen.    ADVANTAGE - The modification-reaction apparatus effectively suppresses the precipitation of carbon and thus requirement of supplying excess amount of water vapor is reduced.    DETAILED DESCRIPTION - A modification-reaction apparatus includes a catalyst layer-including catalyst, and equipped with a water vapor flow path and a raw-materials-and-mineral-fuel flow path. The catalyst layer has a surface (A) and a surface (B) in relation of front and back surfaces. The catalyst accelerates the modification reaction between hydrocarbon-type raw material, mineral fuel and water vapor in modification-reaction apparatus and thus produces gas-containing hydrogen. A water-vapor flow path pours the water vapor along the surface (A) in predetermined direction, and the raw-materials-and-mineral-fuel flow path pours the hydrocarbon-type raw material and mineral fuel along the surface (B).    DESCRIPTION OF DRAWING(S) - The drawing shows the sectional view illustrating typical catalyst layer in modification-reaction apparatus.    Modification-reaction apparatus (10)    Catalyst (20)    Catalyst layer (21)    Surface-A (21a,22a)    Surface-B (21b,22b)    Surface parallel to predetermined direction (23a)    Water vapor flow path (24)    Raw-materials-and-mineral-fuel flow path (26)    Through-hole (42)