To suppress operation quantities necessary for calculating mass property, as for a technology for obtaining mass properties of structures by vibration tests.

An operation device 6 is programmed to execute (A) a step for determining a survey point of estimation object mass property of a measuring object, (B) a step for calculating acceleration at a measuring point as hypothetical acceleration by calculation based on the mass property determined to be a survey point, a vibration force, vibration position where the vibration force is added, and the position of the measuring point, (C) a step for judging if or not specific termination conditions are fulfilled based on the hypothetical acceleration and measured acceleration, (D) a step for adopting the survey point as the eventual mass property of the measuring object when the termination conditions are fulfilled, and (E) a step for executing again the step (B) or the step (D) after modifying a tentative mass property when the termination conditions are not fulfilled.