To obtain the subject latex comprising a vinylidene chloride-based copolymer resin, capable of exhibiting high moistureproofness at low coating levels when applied to building internal trim materials or sheathing materials and having enough blocking resistance to be required in line coating operations.

This latex comprising a vinylidene chloride-based copolymer resin is obtained by emulsion polymerization of a monomer mixture comprising 85.0-93.0 wt.% of a vinylidene chloride monomer and 2.0-14.5 wt.% of at least one kind of another vinyl-based monomer copolymerizable therewith in the presence of 0.5-5.0 wt.% of a reactive emulsifier. This latex thus obtained has a surface tension of 50-70 mN/m.