Biomechanical impedance is relatively small compared to industrial mechanical impedance. Thus it is difficult to measure it precisely. A biomechanical impedance measuring system was developed for portable use by means of random excitation. This system doesn't require a fixed body and vibrator supporting apparatus. In order to obtain an impedance spectrum, the FFT processing is performed using a personal computer. The spectra of the biomechanical impedance which is measured on body surfaces depend on body positions and can be roughly classified into three spectra patterns : soft, stiff and intermediate. During the measurement, the measuring conditions (preload, diameter of the vibrating tip etc.) influence the results. However, it became clear that the linearity of the biomechanical impedance was satisfied in the limited measuring conditions. Accordingly it is possible to standardize the impedance and to compare it with the results under different measuring conditions.