Abstract: A magnetic resonance monitor measures static and extremely low frequency magnetic fields in order to determine the degree of magnetic resonance with the magnetic moments of a biological substrate, more particularly resonance with the magnetic moments of a human body. A digital bandpass filter varies in response to the magnitude of the static magnetic field so that it selects frequencies of the oscillating magnetic field in accordance with the gyromagnetic equation. A spatial analyzer determines the three spatial components of the filtered signals representing the magnetic field oscillating parallel to the static magnetic field vector and the two circularly-polarized components rotating perpendicular to the static field with helicities opposite to each other. A resonance analyzer evaluates accurately the resonance yield which is the change in biochemical processes due to magnetic field exposures.