To provide a configuration of a floor surface cleaning device operable very easily for washing a floor surface, particularly, a carpet.

This floor surface cleaning device is provided with a connection body 23 supporting a pair of rotary brushes 21, 22 in parallel rotatably and pivotally and a motor 3 rotating and driving the rotary brushes 21, 22 in the opposing directions mutually. Central parts 24 on both sides of the connection body 23 are pivotally supported on a support plate 25 of a nozzle main body 1 so as to turn freely, and the rotary brushes 21, 22 are moved vertically by matching with the forward and backward travel operation of the nozzle main body 1. The rotary brush 21 or 22 rotating in the same direction as the direction of travel of the nozzle main body 1 bites a carpet so that the rotary brush on the opposite side floats and the nozzle main body 1 can travel and operate without causing resistance.