To provide an ultrahigh pressure generator which can pressurize an object to be pressurized even at a high pressure of ≥15 GPa, and can be applied even to observational experiment in a high pressure field by a neutron ray, and to provide a member which is used for the ultrahigh pressure generator and stores the object to be pressurized.

The ultrahigh pressure generator is provided with: a first anvil group; a second anvil group 50 arranged in a pressurization space surrounded by anvils in the first anvil group; and a moving means 20 for moving the anvils in the first anvil group. A storage space for storing the object M to be pressurized surrounded by the upper and lower anvil groups is forme in a state where each second anvil forms the second anvil group 50, and in a state where the second anvil group 50 is arranged in the pressurization space, when the anvils in the first anvil group 10 are moved toward the center of the pressurization space, a pseudo hydrostatic pressure field is formed in each second anvil 55.