Provided is a process for purifying human interferon beta from a recombinant human interferon beta-containing culture comprising performing affinity chromatography and cation exchange chromatography, wherein the affinity chromatography includes: adsorbing the interferon beta-containing culture to an equilibrated affinity chromatography column, followed by washing with an equilibration buffer solution; washing the column with a washing buffer solution A of pH 6.5-7.5 containing 30-60 wt % of propylene glycol and a washing buffer solution B of pH 6.5-7.5 containing 10-30 wt % of propylene glycol and 1-2M NaCl; and eluting a human interferon beta-containing fraction with a buffer solution of pH 6.5-7.5 containing 40-60 wt % of propylene glycol and 1-2M NaCl.