PURPOSE: To form the titled reforming device evolving a small amount of soot, having improved durability, by covering its inner wall face with a relatively low-melting material for suppressing the formation of soot, joining contact parts of the inner face with a material for suppressing the formation of soot, having a melting point lower than it.

CONSTITUTION: Chromium, nickel, copper and silver are used as materials for suppressing the formation of soot (the melting temperatures are in the order of chromium>nickle>copper>silver). The film 3 is formed on the inner wall face of the parent material (e.g., SUS304)2 using a relatively high-melting material for suppressing the formation of soot, the parent material is assembled, and the contact parts P of it are welded with a material for suppressing the formation of soot, having a melting point lower than the above-mentioned material, to form the main body 1 of the reactor. The main body 1 of the container is packed with the catalyst 4 (the mark 5 is a permeable fixed plate), methanol vapor introduced from the inlet 6 is brought into contact with the catalyst 4, reformed, to form a combustible gas such as H2, CO, etc., which are taken out from the the outlet 7.