Recently, because the micro-machine is noticed and electronic equipments are made much lighter and smaller, the demand for micro materials is increasing. However the mechanical properties data of the micro materials obviously run short and the evaluation method of micro materials is different according to the researcher. Therefore, the establishment of the test method for the micro materials is very necessary. In this study, the tensile strength tests were carried out using the bonding wires of Cu, Al/Si 1% and Au as the material. Its diameter was 20μm. As the results, in the case of all materials, Young's modulus for gage length of 60mm agreed with that for gage length of 20mm. Therefore, it was found that Young's modulus could be measured with high accuracy. The mean of tensile strength for the bonding wires of Al/Si 1% with gage length of 60mm decreased 3% in comparison with that with gage length of 20mm. But the means of tensile strength for the bonding wires of Cu and Au were unaffected by gage length.
