PROBLEM TO BE SOLVED: To provide a TRPV4 (Transient receptor potential cation channel subfamily V member 4) activator, and a hypotension preventing or improving agent and an autonomic nerve regulator which utilize the efficacy of the TRPV4 activator and serve as means for administration thereof.SOLUTION: A TRPV4 activator comprises Garcinia mangostana extract as an active ingredient. There are also provided a hypotension preventing or improving agent and an autonomic nerve regulator.SELECTED DRAWING: None