PURPOSE: To avoid large bending deformation in order to prevent an insulating ceramic layer from peeling off after the insulating ceramic layer is formed on the surface of a main metal substrate by inserting a wavy spacer into a gap made by folding the main metal substrate several times to form fine flowing routes dividually.

CONSTITUTION: A flat or almost flat metal sheet strip 11 is so folded several times so as to keep a constant gap and be formed into a prescribed outer shape. The main metal sheet 11 formed into the prescribed outer shape is immersed in a ceramic coating liquid 21 to form an insulating ceramic layer 14. Then, a metal sheet 12 bent into an uneven wavy shape is cut into pieces with prescribed length. The resulting wavy spacers 12 of the wavy metal sheet are inserted into each gap 11 of the main metal sheet 11. The spacer 12-inserted assembled body is immersed into a ceramic coating liquid 23 to fix the main metal sheet and the wavy spaceres each other and obtain a desired catalytic converter.