Abstract: A material testing device 1 is constituted by a test piece 2, the mechanical properties of which are to be measured and which is connected to the test piece 2, a pair of torsion bars 4 operating as an elastic support portion of the rotary lever 3 and a frame 5 functioning as a rigid support portion of the test piece 2 and the torsion bars 4 and forming an outside frame, the mechanical properties of the test piece 2 are measured by applying an uniaxial tensile force on the test piece 2 in a direction of arrow marks A--A by applying a vertical load W on one end of the rotary lever 3. The test piece 2 is integrally formed with the frame 5 and the rotary lever 3 and therefore, the mechanical property values can easily be measured with no direct contact to the test piece 2.