Provided are a powder for magnets which gives a rare-earth magnet having excellent magnetic properties and which has excellent compactibility, a process for producing the powder, a powder compact, and a rare-earth/iron/boron alloy material. The powder for magnets is configured of magnetic particles (1) having a structure which comprises a phase (2) constituted of an iron-containing substance and, dispersed therein, grains of a phase (3) constituted of the hydride of a rare-earth element. The phase (2) constituted of an iron-containing substance is evenly present in each magnetic particle (1). This powder hence has excellent compactibility, and a powder compact (4) having a heightened density is easy to obtain therefrom. The powder for magnets is obtained by subjecting a powder of a rare-earth/iron/boron alloy (R-Fe-B alloy) to heat treatment in a hydrogen atmosphere at a temperature not lower than the disproportionation temperature of the R-Fe-B alloy to thereby separate the rare-earth element and an iron-containing substance and yield the hydride of the rare-earth element. This powder for magnets is compacted to obtain a powder compact (4). The powder compact (4) is heat-treated under vacuum to obtain an R-Fe-B alloy material (5). The R-Fe-B alloy material (5) is magnetized to obtain an R-Fe-B alloy magnet (6).