A rotor (4) for a rotary electric machine (1) and having: a plurality of permanent magnets (6), which are axially oriented and are arranged beside one another around a rotations axis (3) so as to form a closed ring; a support cylinder (8), which has an outer surface (9), on which the permanent magnets (6) rest, and a central cavity (12); and two half-shafts (10, 11), which are independent of and separate from one another and are singularly inserted in opposite ends of the central cavity (12) of the support cylinder (8) so as to form one single block with the support cylinder (8). The permanent magnets (6) are circumferentially arranged one following the other according to a Halbach array so as to nullify the magnetic field radially on the inside of the permanent magnets (6) and so as to maximize the magnetic field radially on the outside of the permanent magnets (6).