To provide a vibration-damping and vibration-proof brace which enables reinforcing work to be simply and rapidly performed, which can enhance not only earthquake resistance but also damping and which can be inexpensively attached even to an existing building, a vibration-damping and vibration-proofing method, and a vibration-damping and vibration-proof member.

A vibration-damping and vibration-proof brace 10 includes wire braces 11 and 12. The wire braces 11 and 12 have rotational fitting members 21 fixed on both lengthwise-direction sides of a twisted wire part 20. In the twisted wire part 20, small wire parts are twisted together. The vibration-damping and vibration-proof brace 10 is rotatably attached to a building frame 1 by inserting a fastener through an insertion hole of each of the rotational fitting members 21 in the state of making the respective twisted wire parts of the wire braces 11 and 12 cross each other.