A method for dusting-preventive treatment of a dusting material using a dust-preventive treatment agent including a PTFE aqueous dispersion having lower potential for environmental concerns, which method is as effective as a known method and further has a lower possibility of environmental concerns, and the dust-preventive treated material obtained by treating the dusting material by the method. The method involves mixing a dust preventing treatment composition composed of an aqueous dispersion of polytetrafluoroethylene containing 50 ppm or less of a fluorine-containing emulsifier with the dusting material and then forming fibrils of polytetrafluoroethylene by applying a compression/shear force to the mixture above at a temperature of about 20.degree. C. to 200.degree. C.