A ferromagnetic nano junction element characterized by using two laminates each comprising a nickel thin film having a thickness of 2 nm to 20 nm formed by a vacuum evaporation method on a top surface of a polyethylene naphthalate substrate having the surface roughness equal to or less than 1.6 nm, the nickel thin film having the surface roughness less than 1.6 nm and less than the surface roughness of the polyethylene naphthalate substrate, each of the two laminates having a top portion, a bottom portion, and a side portion positioned between the top portion and the bottom portion, wherein the top portion comprises the nickel thin film, the bottom portion comprises a bottom surface of the polyethylene naphthalate substrate, and the side portion comprises a side edge of the nickel thin film and a side edge of the polyethylene naphthalate substrate and attaching the two laminates to each other to join them so that the nickel thin films cross to each other in such a manner that the side edges of the nickel thin films face each other.