Abstract: The present invention provides a W/O/W type oil adjuvant vaccine containing an outer aqueous phase containing 0.5 wt %-20 wt % of a polyethylene glycol derivative having a molecular weight of 400-20,000, and an inner aqueous phase containing a biologically acceptable and effective amount of an antigen. The constitution of the present invention that a polyethylene glycol derivative having a specific molecular weight is contained in the outer aqueous phase enables preparation of a W/O/W type oil adjuvant vaccine showing a high adjuvant effect, reduced side effects such as topical response, superior preparation stability and superior workability to allow a person to give an injection easily due to the lowered viscosity.

Abstract: A water-in-oil type oil adjuvant vaccine comprises 20 to 90% by weight of an oil phase A) which is in a liquid state at ordinary temperature; 0.5 to 30% by weight of an emulsifying agent comprising a non-ionic surfactant B) which is a partial ester derived from a polyhydric alcohol carrying at least three hydroxyl groups and a fatty acid and which is in a liquid state at 40.degree. C. and a polyoxyethylene (20 to 60 moles) hydroxy fatty acid triglyceride C); and 5 to 75% by weight of an aqueous phase D) containing a biologically acceptable and effective amount of antigens, and optionally E) 0.01 to 10% by weight of an amino acid or a salt thereof and 0.01 to 10% by weight of a non-reducing sugar or a sugar alcohol having at least 5 hydroxyl groups in the molecule. In addition, a water-in-oil-in-water type oil adjuvant vaccine comprises the foregoing water-in-oil type oil adjuvant vaccine as an internal phase and an outer aqueous phase F) comprising 0.