The Fe4N pigments were prepared by nitridation of the Fe pigments in an ahnosphere of ammonia-hydrogen. The Fe pigments, the precursors, were prepared by reduction in hydrogen of the iron oxyhydrates having various particle sizes. The realtionship between the coercivity and the specific surface area of Fe4N pigment was clarified. The relationship between the magnetic properties of the Fe pigments, the precursors, and those of the Fe4N pigments was also clarified. The chemical stabilities of the Fe4N pigment were also investigated. From the results of electron diffraction patterns, it is clear that the Fe4N pigment particle maintains the original shape of the starting material aud that it consists of fine unit particles which link together to form a stereo-network structure, and that the unit particle is observed to be a single crystal, as in the case of the Fe pigment.