Cardiopulmonary resuscitation (CPR) is a first aid to maintain blood circulation in patients with cardiac arrest. When a person performs cardiopulmonary resuscitation, it is difficult to perform CPR with certainly and accuracy. In order to improve the accuracy and safety of CPR, a method is needed to determine whether the patient's chest is wounded and CPR is correctly performed. Mechanical impedance is used as an indicator of the patient's chest characteristics and CPR quality. Preclinical experiments are performed to obtain biometric data to determine the mechanical impedance of the patient's chest and the quality of the CPR. CPR was applied to dummy using manual CPR device to measure CPR execution speed and force. The force was measured by using load-cell, the acceleration rate was measured by using accelerometer, then integrated by using equation and converted to velocity. The frequency characteristics were determined by using Discrete Fourier Transforms of measured force and execution velocity. The mechanical impedance is defined as the ratio of each frequency component of the force to the execution velocity. CPR was performed on dummy of different chest characteristics and different types of mechanical impedance were observed. The mechanical impedance can be used as an index to evaluate the quality of the chest and the quality of the CPR. If it applied to the patient, it will be able to monitor the patient's condition during CPR.