An object of the present invention is to provide a method of controlling
and observing binding of sample substances in an aqueous solution. An
apparatus of the present invention has a unit applying a strong magnetic
field to a sample and an oscillator applying an electromagnetic wave in a
THz field onto the sample. A probe and an observing unit which can bring
about nuclear magnetic resonance in the sample and detect it are
arranged. An electric signal is sent to a THz-ray oscillator to apply an
electromagnetic wave having a resonance frequency of unpaired electron
spin of the sample onto the sample. An electric characteristic of the
nuclear magnetic resonance is detected to observe a binding change in the
sample.
