A honeycomb structural body is constituted with a ceramic block made by arranging a plurality of through-holes side by side in the longitudinal direction through partition walls and sealing either one end portions of these through-holes. The ceramic block of this honeycomb structural body is made of a composite member consisting of ceramic particles and amorphous silicon, so that the honeycomb structural body has an excellent compression strength even if its porosity is increased, and is less in the lowering of mechanical strength even if it is heated to a high temperature, and is excellent in the durability.