An R-T-B based permanent magnet material alloy according to the present invention is an alloy in the shape of a thin plate including R2T14B columnar crystals and R-rich phases (where R is at least one of the rare-earth elements including Y, T is Fe with or without at least one nonferrous transition metal element, and B is boron with or without carbon). In a structure of the alloy as viewed on an arbitrary cross section including a normal to the thin plate, the ratio of the combined area of some of the R-rich phases, which have aspect ratios of 10 or more and the major axes of which define angles of 90±30 degrees with respect to the surface of the thin plate, to the overall area of the R-rich phases included in the alloy is at least 30%.