PURPOSE: To stabilize the titled substance, by adding a polyol to an interferon-β free from glycose chain.

CONSTITUTION: An interferon-β free from glycose chain is stabilized by adding a polyol (e.g. glycerol, ethylene glycol, or sugars such as sucrose) to the interferon in an amount of ≥5%, especially 10W30%. The interferon-β free from glycose chain is G-IFN-β which is a simple protein having a molecular weight of about 20,000 and produced by microorganisms such as Escherichia coli recombined with IFN-β gene.