PURPOSE: To prevent invasion of excessive current into a motor by a method wherein an operation part to contact with a floor surface when a suction head is placed on the floor surface is changed over from a neutral position to an advancing or a retreating position whenever the suction head advances or retreats, and rotation of the motor is reversed accordingly.

CONSTITUTION: An operation part 15 is provided, which comes into contact with a floor surface when a suction head body 1 containing a driving wheel and a rotary brush to be driven by a driving motor is placed on the floor surface. The operation part 15 is formed of an operation lever 17 in a casing 16, an advancing switch 18, a retreating switch 19 and a return spring 20. When the suction head body 1 is placed on the floor surface, the operation lever 17 takes a neutral position. If the suction head body 1 is advanced or retreated (an advancing is shown in the drawing), the operation lever 17 comes into contact with an advancing or a retreating switch 18 or 19. When the operation lever 17 is switched between advancement and retreatment, a neutral state in which no power is supplied to the motor appears temporarily, and then the current flowing direction in the motor is reversed. By this, an invasion of an excessive current into the motor can be prevented, whereby a rectifier for a power source can be protected from being damaged.