To provide a tunnel junction device having a high MR ratio even at room temperature, a tunneling film as a nonmagnetic layer of three-layer structure of LaMnO.sub.3/SrTiO.sub.3/LaMnO.sub.3 is arranged between a ferromagnetic metal material La.sub.0.6Sr.sub.0.4MnO.sub.3 (12) and a ferromagnetic metal film material La.sub.0.6Sr.sub.0.4MnO.sub.3 (14). The tunneling film comprises two unit layers of LaMnO.sub.3 (13A) arranged on the ferromagnetic metal material La.sub.0.6Sr.sub.0.4MnO.sub.3 (12); five unit layers of SrTiO.sub.3 (13B); and two unit layers of LaMnO.sub.3 (13C) arranged at the interface between the SrTiO.sub.3 (13B) and the ferromagnetic metal film material La.sub.0.6Sr.sub.0.4MnO.sub.3 (14).