Provided is a joining structure capable of firmly joining tubes made of different kinds of metal or alloy. The joining structure includes: a needle tube 63 made of a first metal or alloy； a needle 62 made of a second metal or alloy different from the first metal or alloy； a coupling member 66 having a cylindrical shape to provide therein a passage 66a into which the needle tube 63 and the needle 62 are insertable, and having a through hole 66b on a side face thereof to penetrate from outside the coupling member 66 into the passage 66a； and a brazing material 67 injected into the passage 66a through the through hole 66b with an end face of the needle tube 63 and an end face of the needle 62 abutting on each other in the passage 66a to braze the needle tube 63, the needle 62, and the coupling member 66. The second metal or alloy is more easily oxidizable than the first metal or alloy during brazing using the brazing material 67. An abutting position between the needle tube 63 and the needle 62 is deviated from the through hole 66b toward the needle 62 in an extending direction of the needle tube 63 and the needle 62.
