To provide a solid acid superior in solid acid catalyst performance, proton conductivity and ion exchange performance which can exhibit an excellent ion exchange performance, superior performance as a solid acid catalyst, and proton conductivity by using for an ion exchange material, solid polymer electrolyte membrane, electrode catalyst, membrane electrode assembly, and solid polymer fuel cell, and has excellent OH radical resistance and improved durability, to provide a manufacturing method thereof, and to provide the ion exchange material, solid polymer electrolyte membrane, electrode catalyst layer, membrane electrode assembly, and solid polymer fuel cell using the same.

The solid acid is amorphous carbon in which a sulfonic acid group is introduced and has a structure in which a prescribed amount of carbon atoms is substituted by heteroatoms. An organic compound containing heteroatoms or an organic compound which does not contain heteroatoms is heat treated in concentrated sulfuric acid or fuming sulfuric acid to manufacture easily such a solid acid at a reduced manufacturing cost.