Abstract: A hydrogen producing apparatus for producing hydrogen on an industrial scale by steam reforming reactions and separating hydrogen using a hydrogen-permeable membrane, including nested outer (14), intermediate (18) and inner (20) cylinders, a combustion burner (44) disposed toward the inner hollow chamber of the inner cylinder (20), a catalyst layer (A) in the annulus (30) between the intermediate (18) and inner (20) cylinders, hydrogen-permeable tubes (32) disposed in the catalyst layer (A-30), and sweep gas supply tubes (34) in the hydrogen-permeable tubes (32). The raw material gas is fed to the catalyst layer (A) and is converted into hydrogen at a high temperature produced by the burner (44), the produced hydrogen permeates the hydrogen-permeable tubes (32) which selectively separate and collect the hydrogen, and the permeated hydrogen flows with the sweep gas out of the apparatus through the outlet (52) for the sweep tubes (34).