The testing method on the residual strength is not established. The residual strength of soils was obtained using the several shear test apparatus. The residual strength became smaller in the order of pre-cut triaxial test, reversal direct shear test, pre-cut direct shear test, simple shear type ring shear test and direct shear type ring shear test. The influences of restraint conditions and gravel fraction on residual strength were investigated. The residual strength of clayey soils by the simple shear type ring shear test was bigger than one by the direct shear type ring shear test. But the residual strength of the soil containing gravel showed the reverse tendency. This is due to the difference of the restraint condition of a slip surface.