To freely move a suction terminal in a clinic, and to prevent the aperture of an existent piping connected beforehand with the suction terminal from being exposed from a floor surface after removing the suction terminal from a conventional fixed dental treatment waste processing system.

This system is provided with a free arm 1 wherein a suction port for sucking a dental treatment scattered matter is movable; a plurality of arm attaching and detaching mechanism 71 each comprising a tube 81 the upper end of which is opened from a floor surface nearly in a vertical direction and into which the lower end of a free arm mounting pipe 2 constituting one end side of the free arm 1 can be fitted and a lid 82 which can lid the aperture of the tube 81 in an openable and closable manner; and a sending-out tube 72 for sending out the dental treatment scattered matter from the tube 18 to a cleaning device or a sewage through under the floor.