Ceramic particles, fine particles having smaller average particle diameter smaller than that of the ceramic particles and a reduction-resistant material are mixed to obtain a puddle. The reduction-resistant material is a material that is reduced by carbon at a higher temperature as compared with a temperature at which an oxide (for example, silica) of an element contained in the ceramic particles is reduced. The average particle diameter of the ceramic particles is preferably about in a range of 5 to 100 .mu.m and the average particle diameter of the fine particles is preferably about in a range of 0.1 to 10 .mu.m. The reduction-resistant material is, for example, alumina. This puddle is extrusion molded into a honeycomb filter and the molded object is sintered at about 1600 to 2200.degree. C.