The thermal monitoring tool of the present invention has an insertion portion that is inserted into a tissue of a subject, and a predetermined length that the base end portion extends out of the tissue in a state where the insertion portion is inserted into the tissue. A linear member having a distal end portion coupled to the insertion portion； and provided in the insertion portion； engages with the tissue in a state below a predetermined temperature； and from the state below the predetermined temperature to the predetermined portion And a locking portion for releasing the engagement with the tissue by being deformed when heated to a predetermined temperature range exceeding the temperature.本発明の熱モニタリング具は、被検体の組織内に挿入する挿入部と、前記挿入部が前記組織内に挿入された状態において、基端部が前記組織外に延出する所定の長さを有し、先端部が前記挿入部に結合された線状部材と、前記挿入部に設けられ、所定の温度以下の状態において前記組織と係合し、前記所定の温度以下の状態から前記所定の温度を超える所定の温度範囲に加温された場合に変形することで前記組織との係合を解除する係止部と、を含む。
