Abstract: An extrusion die for forming a honeycomb structure such as a catalyst carrier of a catalytic converter for internal combustion engines is provided. The extrusion die includes material inlet ports and latticed slits. The slits are formed in a die base and have first inner walls leading to an outer surface of the die base and second inner walls leading to the material inlet ports, respectively. Metal-plated layers are formed on the first inner walls of the slits to define outlets of the die and have the width smaller than those of the second inner walls of the slits, respectively. This die structure facilities easy extrusion of the honeycomb structure made up by thin honeycomb walls with a smaller extrusion resistance.