To provide a method of polymerizing a vinyl chloride monomer by batchwise suspension polymerization, wherein defective stirring can be prevented when vinyl chloride monomer is additionally charged, less fish eyes are formed in spite of a high bulk specific gravity, and a vinyl chloride monomer excellent in workability can be obtained.

In suspension polymerization by charging, into a polymerization vessel, a vinyl chloride monomer comprising vinyl chloride monomer singly or a monomer composition mainly made up of vinyl chloride monomer together with an aqueous medium, a dispersant, and a polymerization initiator, vinyl chloride monomer and a polyethylene oxide having an average molecular weight of 100,000 to 12,000,000 are added with the amount of the polyethylene oxide being 0.002 to 0.2wt.% based on the vinyl chloride monomer when the polymerization conversion of the vinyl chloride monomer to a polymer during the polymerization reaction is 20 to 80%.