PURPOSE: To enable operation of apparatuses quiet and having less vibration noise, without transmitting any rotational unbalanced vibration to a motor bracket, by constituting the bearing of a rotor with a magnetic bearing of repulsion type using a permanent magnet.

CONSTITUTION: In a rotor 23, since the outsides of permanent magnets 37, 41 are arranged to be S poles and insides of permanent magnets 38, 42 covering those S poles are arranged to be S poles, they repel each other and float aerially by holding clearances. Even if shafts 28, 39 vibrate by the rotation of the rotor 23, the vibration is absorbed in the clearances without being transmitted to the outside permanent magnets 38, 42, so that the vibration of an electrically driven air blower becomes very flow thus a quiet vacuum cleaner may be obtained. On the other hand, in the case of start, that is the initial phase of operation of the rotor 3 or temporary application of inertial force outside to the rotor 23, small ball bearings 36, 40 undertake temporarily the rotation so as to carry out the rotation itself without hindrance, even if repulsion of the magnets is smaller than the inertial force resulting in mutual contact between the permanent magnets 37, 41 and 38, 42 respectively.