This paper presents the results of triaxial compression and extension tests on compacted Kaolin clays under two kinds of constant confining pressures and suction. The test results are uniquely arranged on “Extended Spatially Mobilized Plane (Extended SMP)” with a parameter of σ₀(=c·cot∅). These are the same results when the test results of sands and normally consolidated clays are arranged on the original SMP. And it is concluded from these results that the concept of “Extended SMP” can be applied to the shear behavior of unsaturated soil with constant suction under axisymmetric stress states. The applicability of this concept is the same to the other frictional and cohesive materials like cemented sands and overconsolidated clays.