PURPOSE: To prevent the deformation and movement of a coil, by a method wherein spacers of split into two construction are disposed on the outer periphery of insulating plates being provided around a coil via metallic elastic bodies such as springs, while said spacers hold the elastic bodies and each of the spacers is bonded intimately with each others.

CONSTITUTION: Insulating boards 4A, 4B, 4C, 4D of a material such as FRP are provided around a superconductive coil 3A which is fixed and hardened into a race- track shape by one-body forming by a method such as molding, and the outside of the boards 4AW4D is surrounded by a pair of spacers 5A, 5B which are separated into upper and lower portions and in which holes 6A are made. The insulating boards 4A, 4B have U-shaped cross-section and metal elastic substances 7A, 7B which are made of materials like narrow spring boards are provided between the spacers 5A, 5B and the board surface which is facing the spacers. When the spacers 5A, 5B are mated together, the metal elastic substances 7A, 7B are tightly compressed so that a pre-compression force is imparted to the spacers 5A, 5B. Thus, the superconductive coil 3A is protected from deformation and movement, so that it is fixed and stabilized completely.