A rigid body characteristic identification system which identifies rigid body characteristics of a measurement target including its mass and center of gravity position, provided with an immovable stationary part 10, moving parts 20 which can move with respect to the stationary part and include a measurement target T, support means 30 for supporting the moving parts with respect to the stationary part in a freely vibratable manner, measuring means 40 for measuring data which is necessary for calculating the natural frequency of the moving parts when the moving parts are vibrating, and analyzing means 50 for receiving as input the support conditions by the supporting means and the measurement data which was measured by the measuring means and for performing processing based on these support conditions and natural frequency calculated from the measurement data. The analyzing means uses the support conditions by the supporting means and natural frequencies which are calculated from the measurement data as the basis to identify the rigid body characteristics of the measurement target. Due to this, a rigid body characteristic identification system or rigid body characteristic identification method which can reduce the number of measurement points while identifying the rigid body characteristics with a high precision is provided.