In order to study vibration transmission to the human body and to design seats or suspensions for vibration isolation in the vehicles, a driving point mechanical impedance was measured on various kinds of body postures. A force pickup which was newly developed using a sheet of thin polymer film and an accelerometer were used as a detector for the impedance measurement. An instrument with analogue computing circuits was also employed, which could automatically calculate the im-pendance and draw an impedance chart expressed by magnitude and phase within 90 sec after the start of measurement

The mechanical impedance were measured in the frequency range from 3 to 200 Hz on kneeling, sitting, and standing postures and in addition, at local parts of the body such as the head, hands, and legs. Because of contraction of measur-ing time, the impedances even in unstable postures were able to be measured. As a result, the difference of mechanical impedance was clarified among various sorts of the postures, and transmission mechanism of the vibration in the body could be estimated through the change of the mechanical impedance.