Relating to the production of powder compact materials, uneven packing structure of consolidated powder bed was experimentally investigated under piston press through stress propagation characteristics. Measuring the bottom pressure in a cylinder under various conditions, the vertical pressure distribution was approximately expressed in the axial and lateral directions on the basis of author's equation of solids pressure derived for compressible powders. As a result, it was confirmed that the rate of propagation of the compressive pressure applied onto the powder bed surface decreases with increasing bed thickness, the smaller diameter of the cylinder and the higher overall packing density. The nressure was also found to decrease along the radius.