Paying attention to cobalt-based amorphous alloy as magnetic shielding material to replace permalloy, the authors attempted to modify materials suitable for magnetic shielding by heat treatment. Furthermore, magnetic shaking technique was applied. As a result, incremental magnetic permeability could be increased to about 59.5 times that of permalloy. Next, the magnetically shielded room using cobalt-based amorphous alloy was developed. It was confirmed that shielding performance was greatly improved as a result of fabrication of magnetic shield modules, coupling them to fabricate magnetic shield panels, and adding them as magnetic shielding layers to an established magnetically shielded room.