PURPOSE: To simply produce molybdenum nitride having a high critical temp. by feeding Mo to the surface of a substrate while projecting ion beams contg. N to form a thin film.

CONSTITUTION: While ion beams 3 contg. N are projected, Mo particles 2 are fed to the surface 1 of a substrate 10 to form a film. Since activated N is fed as the ion beams 3, NaCl type molybdenum nitride is formed. The ion beams 3 collide against the surface 1 with kinetic energy and it is supposed that nonequilibrium NaCl type molybdenum nitride is liable to be formed by the shock of the collision. By this invention, superconductive molybdenum nitride having a high critical temp. and useful for a Josephson device, a superconductive magnet or wire is obtd.