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The Biomagnetism measurement is required shielding effect 1/S≦1/10 −7 for using SQUID magnetometer. The superconducting shield is possible to realize ideal low magnetic noise space. But it is required to attenuate every external field inside the superconducting hollow cylinder equally. Especially, radial external field decreases gently comparison to axial field. At this time the length of cylinder needs 4.4 m for diameter 1 m to realize shielding effect 1/S≦1/10 −7 . On the other hand, it is only 2.1 m for axial field. For that reason, we devised two methods to attenuate radial field rapidly coupled with permalloy. K E Y W O R D Sbiomagnetism, magnetic shield, permalloy, permeability, SQUID, superconductor Electr Eng Jpn. 2019;207:3-14.

The Biomagnetism measurement is required shielding effect 1/S≦1/10 −7 for using SQUID magnetometer. The superconducting shield is possible to realize ideal low magnetic noise space. But it is required to attenuate every external field inside the superconducting hollow cylinder equally. Especially, radial external field decreases gently comparison to axial field. At this time the length of cylinder needs 4.4 m for diameter 1 m to realize shielding effect 1/S≦1/10 −7 . On the other hand, it is only 2.1 m for axial field. For that reason, we devised two methods to attenuate radial field rapidly coupled with permalloy. K E Y W O R D Sbiomagnetism, magnetic shield, permalloy, permeability, SQUID, superconductor Electr Eng Jpn. 2019;207:3-14.

Superconducting shield which has wall thickness over London penetration depth can realize zero field environment in principle. But in policrystal superconductor, to contact with Josephson junction between crystals, critical current density is smaller , equivalent penatration depth is longer. Consequently it is possible that external magnetic field penetrate through a superconductive wall and deteriorate shielding property. We applied equivalent penetration depth to magnetic field determination method of superconductor and performed measurement of leakage field in BiSrCaCuO(2212 phase) superconducting hollow cylinders. As the result of that, leakage field was observed and the shielding effect is similar to analysis. In spite of that, we show that superconductor has good shielding property superior to ferromagnetic and can improve the limited shielding property by coupling to ferromagnetic.