Since late 1990's, the reliability of temperature measurements at high temperatures was remarkably upgraded by establishing the national metrology standards for calibration of thermocouples up to 1550 °C, and by implementing the traceability system. The traceability system, structured as a hierarchical link of calibrations between the national metrology standards and practical measurements, was designed in consideration of various elements such as availability of the measurement standards and sharing the responsibility with accredited calibration laboratories. The optimized scheme for industries in Japan was established by promoting a balanced combination of conventional techniques held by accredited calibration laboratories and progressive technology, taking into account the spread of the progressive technology. キーワード：熱電対、計量標準、校正、温度定点、共晶点Keywords：Thermocouple, measurement standard, calibration, temperature fixed point, eutectic point 産業技術総合研究所 計測標準研究部門 〒 305-8563 つくば市梅園 1-1-1 中央第 3