Vibration damping device and design method of the same

A designing method of a vibration damping device comprising:

• a supporting member that rotates integrally with a rotation element, to which torque from an engine is transmitted, around a rotation center of the rotation element;
• a restoring force generation member that is coupled to the supporting member so as to transmit and receive torque to and from the supporting member and that is configured to swing in accordance with rotation of the supporting member;
• and
• an inertia mass body that is coupled to the supporting member via the restoring force generation member and that swings around the rotation center in conjunction with the restoring force generation member in accordance with rotation of the supporting member, in which the restoring force generation member swings around a swing center that is set so that a relative position with respect to the inertia mass body does not change, wherein
• a trajectory of a center of gravity of the restoring force generation member is set so that a distance between the center of gravity and the swing center changes in accordance with a change in a swing angle of the restoring force generation member with respect to the inertia mass body.