In the present invention, a non-uniform applied magnetic field is used to magnetize a bulk magnet structure with a magnetic field having high uniformity. Provided is a bulk magnet structure that comprises at least one ring-shaped oxide superconducting bulk body, that is configured by layering ring-shaped oxide superconducting bulk bodies or columnar oxide superconducting bulk bodies, and that has fitted thereto at least one outer circumferential reinforcing ring covering the outer circumferential surface of the bulk magnet structure. Also provided is a magnetization method for a bulk magnet structure including a basic magnetization step in which the strength of a magnetic field applied to the aforementioned bulk magnet structure is decreased while the bulk magnet structure is held in a superconducting state by a temperature controller. After the basic magnetization step, the bulk magnet structure is magnetized by controlling at least one of the temperature controller and a magnetic field generator so that a u