To reduce noise while enhancing the pump performance by press fitting an armature shaft to the inner ring of a first bearing on one end side thereof and to the inner ring of a second bearing on the other end side thereof under a state where the outer rings of the first and second bearings are pressfitted, respectively, to the yoke and the pump housing.

The armature shaft 4 of a motor 1 has one end side born rotatably on the yoke 2 side through a first bearing 9 and the other end side born rotatably on the pump housing 3 side through a second bearing 11. The first bearing 9 has inner and outer rings 9a, 9b fitted, respectively, to one end side of the armature shaft 4 and to the tubular part 2b at the bottom of the yoke. The second bearing 11 has inner and outer rings 11a, 11b press-fitted, respectively, to the other end side of the armature shaft 4 and to the second shaft supporting part 3b of the pump housing 3. Misalignment between the bearings 9, 11 is absorbed at the spigot joint of the yoke 2 and the pump housing 3 thus suppressing noise.