PURPOSE: To separate and measure each nuclear magnetic parameter on real- time basis by obtaining the function of one nuclear magnetic parameter from information on a nuclear magnetic material extracted from a specific position of a sample by nuclear magnetic resonance.

CONSTITUTION: The sample 2 to be measured is placed between magnets 1 and 1' and focus magnetic field coils 4 and 4', and pulses are applied from a pulse generator 8 to a gate circuit 9 connected to a high-frequency oscillator 10 to apply high-frequency pulses to a coil 6. Then, a free inductive attenuation signal is inputted to a central processing controller 7 through a phase detector 14 and an A/D converter 15 to calculate the ratio between the DC component of this signal and another proper frequency component, finding an actual relief time from the relief time dependency of the ratio. Then, the influence of the relief time is removed from the DC component to calculate heat-balanced magnetism. Thus, one nuclear magnetic parameter is obtained from the function of plural nuclear magnetic parameters.