The shielding performance of a magnetically shielded room (MSR) for bio-magnetic measurement was evaluated using JEITA standard (EM-4502 and EM-4503). In the process of evaluation, some problems were extracted, such as the fact that the MSR shape was not covered by the standard. Therefore, the authors revised EM-4502 and EM-4503. The main points of revision are the expansion of the target MSR shape and the reexamination of the placement conditions and accuracy of the exciting coils. Finally, EM-4502A and EM-4503A formulated as JEITA revised standards were used to reevaluate the shielding performance of the aforementioned MSR.
