In a compression test of kneaded wet powder in a cylinder to evaluate the result of kneading, the ratio of pressure p(L) at the bottom of the cylinder to the pressure p(u) under the pressing stamp changes with the height of compressed powder. By assuming the dependence of friction muK between powder and cylinder wall upon pressure, the relation between the ratio p(L)/p(u) and the height of powder was analysed for both compression under constant pressing velocity and compression under constant pressure, and the analysis was confirmed by experimental data.