Rotary inertia mass damper

To provide a rotary inertia mass damper, which is capable of reducing an axial reaction force that is generated due to vibration having an excessive acceleration to the extent possible when the vibration is input, and of preventing breakage of the damper itself or a construction, provided is a rotary inertia mass damper, including: a first coupling portion, which is fixed to a first structure; a second coupling portion, which is coupled to a second structure; a screw shaft, which has one axial end connected to the first coupling portion and retained so as to be non-rotatable; a fixed barrel, which has a hollow portion for receiving the screw shaft, and is connected to the second coupling portion; and a rotary body, which is retained so as to be freely rotatable relative to the fixed barrel, is threadedly engaged with the screw shaft, and is configured to reciprocally rotate in accordance with advancing and retreating movement of the screw shaft relative to the fixed barrel. A torque limiting member is provided between an axial end of the screw shaft and the first coupling portion, and is configured to, when a rotational torque that exceeds a predetermined value is applied to the screw shaft, allow rotation of the screw shaft relative to the first coupling portion to reduce a rotation angle of the rotary body.