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.