of substantially inverted v shape respectively having edges 29a and 29b and edges 30a and 30b respectively parallel to lines l l and m m extending in directions respectively perpendicular to arrow directions a and b which are mutually perpendicular and are at angles of 45 45 degrees with a line vertical to a record disc accordingly the regions of the yoke faces 23a and 26a in the vicinity of the lower end part thereof are confronting the upper half parts 19au and 19bu of the coils 19a and 19b of the coil plate 17 the upper edges 31a 31b 32a and 32b of the yoke faces 24a and 27a of the yokes 24 and 27 are formed to be spaced apart from and parallel to the above mentioned lower edges 29a 29b 30a and 30b of the yoke faces 23a and 26a accordingly the regions of the yoke faces 24a and 27a in the vicinity of the their upper ends are confronting the lower half parts 19al and 19bl of the coils 19a and 19b of the coil plate 17 the magnets 22 and 25 respectively have magnetic poles at their upper and lower ends and are so disposed that the polarities of their upper and lower ends are mutually opposite for example in the illustrated example the magnetic poles of the upper and lower ends of the magnet 22 are n and s poles while the magnetic poles of the upper and lower ends of the magnet 25 are s and n poles accordingly in the case of the present example a magnetic flux 33 is produced between the yokes 23 and 26.