PURPOSE: To obtain a slip agent for water-based coating material which can decrease the coefficient of friction of coating film to increase its slipperiness and to suppress the occurrence of marks produced by scratching and rubbing by dispersing a hydrophilic wax combined with a hydrophilic solvent in the form of fine particles in water.

CONSTITUTION: At least one hydrophilic wax selected from among natural waxes such as shellac wax, sugar wax, beeswax, carnauba wax and montan wax and synthetic waxes such as oxidized paraffin, oxidized microcrystalline wax, oxidized polyethylene and ethylene acryllic wax is dissolved under heating in a hydrophilic solvent selected from among an alcohol, cellosolve and other water-soluble or partially water-soluble volatile solvents. The obtained hot solution is added to a mixed solution comprising a hydrophilic solvent and water to form a primary dispersion. This dispersion is ground into a fine particle dispersion of a maximum particle diameter of 20μm or below.