Elastic modulus and internal friction measurements using the piezoelectric-composite-bar method were established. The resonance conditions of the composite bar consisting of a piezoelectric crystal and a sample were measured using an impedance analyzer, and investigated using a personal computer. The above system made it possible to measure with a small sample highly accurately and easily. We measured the elastic moduli and internal friction of some materials using this method. 1) The elastic moduli of Ni showed a marked temperature dependence on ferromagnetic phase transition. 2) Young's moduli of Pb-Sn solder alloys depended on their compositions and temperatures. 3) There was no elastic anomaly on the Ti-based metal-matrix-composite reinforced with TiB. 4) The internal friction of zirconia ceramics added with Y₂O₃ or CeO₂ was studied. It was found that the oxygen vacancy played an important role on elastic property of zirconia ceramics.