PURPOSE: To obtain a magnetic shielding device which is large in size, high in shielding capacity, and easily produced by a method wherein small superconducting boards are combined into one piece.

CONSTITUTION: Superconducting boards 4 are combined into one piece for the formation of a magnetic shielding device, where a superconductor 3 is provided to both or either of the surfaces of a metal plate 1 excluding its peripheral points 2 to constitute the superconducting board 4, and the adjacent superconducting boards 4 are jointed together electrically connecting the joints 2 of them with each other. Therefore, a magnetic shielding device large in size and small in weight can be easily formed at a low cost. That is, a magnetic shielding room or the like suitable in size and shape for uses can be easily manufactured only by changing the superconducting boards 4 in number and connecting ways such as connecting directions.