Provided are high purity sodium p-styrenesulfonate with an excellent hue which is useful as a reactive emulsifier or dispersant for producing a polymer emulsion, or synthetic starch for clothing ironing and poly(sodium p-styrene-sulfonate) with an excellent hue using the same or sodium p-styrenesulfonate improved in fluidity while keeping good solubility.An aqueous p-β-bromoethylbenzenesulfonic acid solution and an aqueous sodium hydroxide solution are reacted under specific conditions to control the particle size, thereby obtaining sodium p-styrenesulfonate particles improved in a balance between fluidity and solubility, and further, impurities such as isomers are reduced, thereby obtaining high-purity sodium p-styrenesulfonate with an excellent hue.