A rare earth-iron-nitrogen-based magnetic powder according to this invention contains, as main constituent components, a rare-earth element (R), iron (Fe), and nitrogen (N). Moreover, this magnetic powder has an average particle size of 1.0-10.0 μm, and contains 22.0-30.0 mass % of a rare-earth element (R) and 2.5-4.0 mass % of nitrogen (N). Further, this magnetic powder includes: a core part having any one crystal structure among a Th2Zn17 type, a Th2Ni17 type, and a TbCu7 type; and a shell layer provided on the surface of the core part and having a thickness of 1-30 nm. The shell layer contains a rare-earth element (R) and iron (Fe) so that the R/Fe atomic ratio is 0.3-5.0, and further contains 0-10 at % (exclusive of 0) of nitrogen (N). Furthermore, this magnetic powder contains compound particles composed of a rare-earth element (R) and phosphorus (P).