To provide a cooling system and a magnetoencephalogram having good cooling efficiency by reducing invasion of heat to a connecting portion for carrying a refrigerant.

The cooling system is provided with a container 1 for storing an SQUID sensor and a refrigerant for cooling the SQUID sensor, a refrigerant condensation part, a thermal radiation shield part, a magnetic shield part, a condensation refrigerator, a magnetic shield refrigerator, a condensation refrigerant supply passage 8a, a condensation refrigerant return passage 9a, a magnetic shield refrigerant supply passage 10a, a magnetic shield refrigerant return passage 11a and an outer shell pipe 20. Three passages of the condensation refrigerant supply passage 8a, the condensation refrigerant return passage 9a, the magnetic shield refrigerant supply passage 10a and the magnetic shield refrigerant return passage 11a are surrounded by a heat insulating space 50 provided inside an inner pipe 11s, respectively, and the other one passage other than the three passages forms a passage surrounding the heat insulating space 50 and having an annular cross section. A space between the other one passage and the outer shell pipe 20 is a vacuum region 60.

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