Abstract
First, the historical development of high pressure NMR for solution studies has been reviewed; it has been started by Benedek-Purcell, developed extensively by Jonas, and expanded further by Yamada and some others in several countries with different purposes as a versatile tool for studying structure, phase transitions, dynamics, and reactions at high pressure. Second, the characteristic features of modern NMR spectroscopy are described. Third, the new high pressure NMR machine, recently constructed by the Research Grant-in - Aid for the Priority Area of Nonequilibrium Processes in Solution, has been illustrated, together with the reliability test and some experimental results on the spin - lattice relaxation time for heavy water. Fourth, it is confirmed that the rotational relaxation time is sensitive to the water structre due to anisotropic hydrogen bond interactions.