Three kinds of specimen, consisting of the graded pyrophyllite particles alone, a substituent of 8 percent fire clay for the finer portion ($F_2$) of it, and 0.8 percent inorganic binder-added composite were prepared under the following conditions respectively; moisture content=4.5~5.0%, forming pressure=250kg/$ extrm{cm}^2$ and sintering temperature=1, 000~1, 30$0^{circ}C$. The various properties such as modulus of rupture, apparent porosity, bulk specific gravity, pore size and pore distributiion were measured in order to collaborate with sintering phenomena. The results obtained are as follows: (1) Apparent porosity isgradually decreased with rising the sintering temperature to 1, 25$0^{circ}C$. (2) The binder-added specimen showed the lowest value in porosity. (3) The optimum sintering temperature of specimens was considered to be 1, 25$0^{circ}C$. (4) The wider differences between pore volumes of specimens could be obtained by method of mercurypenetration porosimeter than by the conventional method for porosity.