PROBLEM TO BE SOLVED: To provide a non-invasive muscle fatigue evaluation method and a muscle fatigue evaluation system capable of accurately evaluating muscle fatigue generated when a non-constant load is applied to a specific muscle. SOLUTION: A first voltage V generated when at least two electrodes 10 and 20 are arranged on the surface of a living body at a predetermined interval and a first external resistor Rg1 is connected in parallel between the two electrodes. The second voltage V 2 generated when 1 and the second external resistor Rg 2 are connected in parallel is measured, and based on the voltage ratio V 1 / V 2 of the first voltage V 1 and the second voltage V 2. , The biovoltage between two electrodes in the muscle part under the surface of the living body is calculated, and the local muscle fatigue in the muscle part is evaluated based on the time change of the calculated biovoltage. [Selection diagram] Fig. 2【課題】特定の筋肉に一定でない負荷をけたときに生じる筋肉の疲労を、精度良く評価することができる非侵襲性の筋疲労評価方法及び筋疲労評価システムを提供する。【解決手段】生体表面に、少なくとも２つの電極１０、２０を、所定の間隔を開けて配置し、２つの電極間に、第１の外部抵抗Ｒg1を並列接続したときに生じる第１の電圧Ｖ１、及び第２の外部抵抗Ｒg2を並列接続したときに生じる第２の電圧Ｖ２を測定し、第１の電圧Ｖ１及び第２の電圧Ｖ２の電圧比Ｖ１／Ｖ２に基づいて、生体表面下の筋肉部位における２つの電極間の生体インピーダンスを算出し、算出した生体インピーダンスの時間変化に基づいて、筋肉部位における局所的な筋疲労を評価する。【選択図】図２
