A rare earth-iron-nitrogen-based magnetic powder comprising a rare earth element, R, iron, Fe, and nitrogen, N, as main constituents, the magnetic powder having an average particle size of 1.0 μm or more and 10.0 μm or less, wherein the average particle size is measured with a laser diffraction particle size distribution analyzer, and having a rare earth element, R, content of 22.0% by mass or more and 30.0% by mass or less and a nitrogen, N, content of 2.5% by mass or more and 4.0% by mass or less, wherein the contents of rare earth, R, and nitrogen, N, in the magnetic powder are determined by inductively coupled plasma emission spectroscopy and thermal conductivity techniques, respectively, the magnetic powder comprising magnetic particles comprising: a core having a crystal structure selected from the group consisting of Th 2 Zn 17 -type, Th 2 Ni 17 -type, and TbCu 7 -type crystal structures, wherein the crystal structure of the powder is evaluated by powder X-ray diffraction using a Cu target at an acceleration voltage of 45 kV, a current of 40 mA, and a 2θ scanning speed of 2 min/deg; and a shell layer having a thickness of 1 nm or more and 30 nm or less and provided on a surface of the core, the shell layer containing a rare earth element, R, and iron, Fe, in an atomic ratio R/Fe of 0.3 or more and 5.0 or less and having a nitrogen, N, content of more than 0 at% and 10 at% or less, the magnetic powder further comprising particles of a compound comprising a rare earth element, R, and phosphorus, P, wherein the composition and the average thickness of the shell layer are analyzed and evaluated using a transmission electron microscope at an acceleration voltage of 200 kV and an energy dispersive X-ray spectroscopy detector, characterized in that the shell layer has a two-layer structure comprising an outer layer and an inner layer, the outer layer comprises oxygen, O, and calcium, Ca, in addition to the rare earth element, R, iron, Fe, and nitrogen, N, and the inner layer comprises oxygen, O, in addition to the rare earth element, R, iron, Fe, and nitrogen, N, and is free of calcium, Ca, and the outer layer has an atomic ratio R/Fe of A, the inner layer has an atomic ratio R/Fe of B, and B < A is satisfied. the magnetic powder having an average particle size of 1.0 μm or more and 10.0 μm or less, wherein the average particle size is measured with a laser diffraction particle size distribution analyzer, and having a rare earth element, R, content of 22.0% by mass or more and 30.0% by mass or less and a nitrogen, N, content of 2.5% by mass or more and 4.0% by mass or less, wherein the contents of rare earth, R, and nitrogen, N, in the magnetic powder are determined by inductively coupled plasma emission spectroscopy and thermal conductivity techniques, respectively, the magnetic powder comprising magnetic particles comprising: a core having a crystal structure selected from the group consisting of Th 2 Zn 17 -type, Th 2 Ni 17 -type, and TbCu 7 -type crystal structures, wherein the crystal structure of the powder is evaluated by powder X-ray diffraction using a Cu target at an acceleration voltage of 45 kV, a current of 40 mA, and a 2θ scanning speed of 2 min/deg; and a shell layer having a thickness of 1 nm or more and 30 nm or less and provided on a surface of the core, the shell layer containing a rare earth element, R, and iron, Fe, in an atomic ratio R/Fe of 0.3 or more and 5.0 or less and having a nitrogen, N, content of more than 0 at% and 10 at% or less, the magnetic powder further comprising particles of a compound comprising a rare earth element, R, and phosphorus, P, wherein the composition and the average thickness of the shell layer are analyzed and evaluated using a transmission electron microscope at an acceleration voltage of 200 kV and an energy dispersive X-ray spectroscopy detector, characterized in that the shell layer has a two-layer structure comprising an outer layer and an inner layer, the outer layer comprises oxygen, O, and calcium, Ca, in addition to the rare earth element, R, iron, Fe, and nitrogen, N, and the inner layer comprises oxygen, O, in addition to the rare earth element, R, iron, Fe, and nitrogen, N, and is free of calcium, Ca, and the outer layer has an atomic ratio R/Fe of A, the inner layer has an atomic ratio R/Fe of B, and B < A is satisfied.