A nozzle assembly usable with an upright vacuum cleaner, comprising: a nozzle assembly body; a drum brush unit disposed in the nozzle assembly body, the drum brush unit having a drum brush disposed to move dirt or dust adhered to a surface to be cleaned while coming in rotational contact therewith; a subsidiary brush unit disposed in front of the drum brush unit, and the subsidiary brush unit having a subsidiary brush to preliminarily move the dust or dirt adhered to the surface to be cleaned before the drum brush moves the dirt or dust adhered to the surface to be cleaned; and a locking unit disposed to the drum brush unit to selectively fix the subsidiary brush unit to the drum brush unit, wherein the subsidiary brush unit is rotatably connected to the drum brush unit to selectively maintain a contact state or a non-contact state to the surface to be cleaned, and, when the subsidiary brush unit maintains the contact state to the surface to be cleaned, the locking unit fixes the subsidiary brush unit to the drum brush unit.