A die for extruding honeycomb structural bodies includes a plurality of ceramic batch exhaust grooves and a plurality of ceramic batch supply apertures. Tubes are fitted in at least some of the ceramic batch supply apertures to improve or make constant the surface roughness and dimensions of inner surfaces of ceramic batch supply apertures through which the ceramic batch passes, thereby producing perfect ceramic honeycomb stuctural bodies. The adjustment of flow of ceramic batch is so simplified that any other controlling plate which would be required in the prior art is not needed for controlling the flow. When the supply apertures have been worn off, the tubes are exchanged by new ones to restore the required inner surfaces easily.