To easily adjust the uniformity of a magnetostatic field area by using a magnetic adjuster even after a device is installed.

To magnetic adjuster fixing plates 42A-47A and 42B-47B, the magnetic adjusters 42A-47A and 42B-47B for adjusting the uniformity of a magnetostatic field in the magnetostatic field area are attached at prescribed positions. The magnetic adjuster fixing plates 42A-47A and 42B-47B to which the magnetic adjusters 42A-47A and 42B-47B are attached are inserted from insertion ports provided on the side faces of magnetic plates 25A and 25B. Thus, even after the device is installed, the uniformity of the magnetostatic field in the magnetostatic field area is adjusted by inserting the magnetic adjuster fixing plates 42A-47A and 42B-47B even without detaching gradient magnetic field coils 28A and 28B.