PURPOSE: To save the power and to lower the noise, and also, to improve the operability of a suction port by providing two sets of pressure sensors between a gate of a programmable single junction transistor and a grounding conductor and between the anode and a high voltage line.

CONSTITUTION: When a switch 14 is turned on to the side of a resistance 10a and a switch of the vacuum cleaner is turned on, and the suction port is separated from the floor, static pressure in a dust collecting passage becomes small, an electric resistance of pressure detecting elements 18, 19 becomes large, and a combined electric resistance with semi-fixed resistance 20, 21 becomes the maximum value. A current flowing through the large combined electric resistance of a second pressure sensor 12 is small, many hours are required until the potential of a capacitor 13 becomes larger than the potential of a gate G2 of a first pressure sensor 11, a programmable single junction transistor 16 conducts and a current flows between the anode A and the cathode K, when the current starts to flow to a primary side winding 51 of a pulse transformer 5 becomes later than the zero crossing point of a power source formed by a sine wave, and a rotation of an air blasting motor 1 becomes a low speed. When the suction port is fixed to the floor, the combined electric resistance with the semi-fixed resistances 20, 21 becomes an intermediate value, and the air blasting motor 1 rotates at a high speed.