PROBLEM TO BE SOLVED: To provide a caulking structure of a metal material which allows for stable and strong bonding between metal materials, while reducing the electrical resistance even if the metal materials to be bonded are different kind of materials from each other.SOLUTION: The caulking structure of a metal material includes a metal plate 12 through which a hole 14 is bored, and a disc-like conductive member 13 which is fitted in the hole 14 and then caulked to the periphery thereof. A groove 17 is provided in the periphery of the hole 14 at least on one side thereof, and a vertical flange 21 projecting from at least one side is provided on the outer periphery of the conductive member 13. When the conductive member 13 is fitted in the hole 14 and then caulked to the metal plate 12, the vertical flange 21 of the conductive member 13 is collapsed, and the groove 17 of the metal plate 12 is filled with the vertical flange 21 thus collapsed.