The present invention relates to a processing aid of a non-fluorinated melt-processable polymer and a masterbatch for a processing aid, features the inclusion of a processing aid comprising a fluoropolymer forming clustered secondary particles each having a particle size of 2 μm to 2 mm and being a combination of primary fluoropolymer particles each having a diameter of 0.02 μm to 0.5 μm, and may accelerate the elimination of melt fracture despite the omission of an interfacial agent and decrease extrusion load upon process to thereby enhance productability.