To obtain an electronic system which is constituted by housing an electronic device that is cooled to a temperature of 150 K or lower for operation in a heat insulating vacuum vessel and can operate the electronic device by efficiently cooling the device to a desired temperature, by efficiently suppressing the heat flowing in the vessel from the outside through wiring for signal and securing cooling power of a cooling means.

An electric system is constituted by housing an electronic device 13, which is cooled to a temperature of 4-150 K for operation in a vacuum vessel, 11, while the device 13 is placed on a cooling means 12 and electrically connecting the device 13 to an external electric circuit through wiring 14 for signal. The wiring 14 has a high heat resistance section 15, having a heat resistance of 1.25 k/W per mm length of a conductor between the wall of the vessel 11 and device 13 or higher and the whole body of the conductor has a heat resistance of 125 k/W or higher and a transmission loss of 1 dB or smaller with respect to high-frequency signals between 100 MHz and 60 GHz. Since heat flowing in the vessel 11 from the outside via the wiring 14 can be suppressed efficiently, the device 13 can be cooled efficiently to a desired temperature for operation with the cooling means 12, even when the means 12 has small cooling power.