A rotor for a rotary electrical device to be arranged to face to a stator, comprises a rotor iron core extending axially and including a plurality of slots arranged with a predetermined circumferential interval, a rotor coil contained by the slots, a coil support member of electrically insulating property arranged between parts of the rotor coil at an axial end of the rotor coil, and a retaining ring covering the coil support member and the axial end of the rotor coil, the coil support member has two fitted portions and a connecting portion connecting the fitted portions to each other to form H-shape of cross section and to form a space between the rotor coil and each of opposite sides of the connecting portion, and the coil support member further has a communicating path communicating to the spaces.