A gel permeation column is a chromatography column which is used in gel permeation chromatography and which employs as the stationary phase a swollen gel made by polymerizing and cross-linking styrene in the presence of a diluent which is a nonsolvent for the styrene polymer. The polymer to be analyzed is introduced at the top of the column and then is elutriated with a solvent. The polymer molecules diffuse through the gel at rates depending on their molecular size.