A connection structure includes a multi-thread coil formed by winding first metal element wires formed of a first metal and second metal element wires formed of a second metal arranged between a first metal body including the first metal and a second metal body including the second metal. The first metal body is connected to the first metal element wires of the multi-thread coil, and the second metal body is connected to the second metal element wires of the multi-thread coil. The connection structure imparts improved flexibility to the connection between the first and second metal bodies, and an appropriate connection can be provided even when the first and second metal bodies are made of dissimilar metals.