To provide a spring structure not resulting in any communication failure because a line between the connections in the line side and apparatus side is shut off even in the case where a spring plug and a spring jack in either side of a channel panel and a testing panel are loaded first.

A spring apparatus enables connection between a spring jack 2 provided to a channel panel 1 and a spring jack 4 provided to a testing panel 3 via a spring code 5. In this spring apparatus, the spring jacks 2, 4 are constituted including pins forming pairs 8a, 8b, 11a, 11b in the jack side that are normally in contact and are not in contact when the spring plugs 15, 16 of the spring code 5 are inserted and insulating projected portions 9, 12 provided in the internal side of the pair of jacks. Moreover, the spring plugs 15, 16 of the spring code 5 are constituted including pins forming pairs 17a, 17b, 18a, 18b of the plug side electrically connecting the jack side pins through insertion between the jack side pins and are normally in contact but is not in contact when the insulating projected portions 9, 12 are inserted.