Vanadium oxides exhibit rich behaviors under high-pressure, for examples, the pressure-temperature (P-T) phase diagram of V2O3 as a prototype of Mott-Hubbard model, a "devil's flower" phase diagram of NaV2O5 derived from the ANNNI model, the pressure-induced superconductivity adjacent to charge order in beta-A(0.33)V(2)O(5) (A = Li, Na, Ag), a rich P-T phase diagram including the spin-gaped phases with devil's staircase type superlattice modulations in beta-Sr0.33V2O5, etc. These results reveal that various ground states compete in vanadium oxides and high-pressure give a perturbation to such competition.