Provided are ultra-low-field nuclear-magnetic-resonance myocardial electrical activity detection method and an ultra-low-field nuclear-magnetic-resonance device. The ultra-low-field nuclear-magnetic-resonance device includes magnetic shielding means high-sensitivity magnetic field measuring means disposed adjacent to a measurement target disposed inside the magnetic shielding means and bias magnetic field generating means for providing an external measurement bias magnetic field, corresponding to a proton magnetic resonance frequency (nuclear magnetic resonance frequency) corresponding to a frequency of periodic myocardial activity of a lesion desired to be measured, to the measurement target. The high-sensitivity magnetic field measuring means measures a magnetic resonance signal generated from the measurement target.本発明は、極低磁場核磁気共鳴心筋電気活動直接検出方法及び極低磁場核磁気共鳴装置を提供する。この極低磁場核磁気共鳴装置は、磁気遮蔽手段、磁気遮蔽手段の内部の配置される測定対象に近接して配置された高感度磁場測定手段、及び測定対象に測定しようとする病巣の周期的心筋電気活動の周波数に該当する陽子磁気共鳴周波数(核磁気共鳴周波数)に該当する外部測定バイアス磁場を提供するバイアス磁場発生手段を含む。高感度磁場測定手段は、測定対象から発生される磁気共鳴信号を測定する。
