An influenza virus vaccine comprising oil-in-water emulsion adjuvant is known, which can reduce dosage of the emulsion adjuvant required by the influenza virus vaccine so as to prepare more vaccines with a given amount of emulsion and/or miniaturize the amount of produced emulsion that is necessary for obtaining the given amount of vaccine dosage. These vaccines can be conveniently prepared by blending (i) the oil-in-water emulsion and (ii) aqueous products of influenza virus antigen. In one hand, ingredients (i) and (ii) having substantially identical volume are employed in the other hand, the ingredients (ii) having excess volume can be utilized. When the substantially identical volume is applied, concentration of hemagglutinin of the ingredients (ii) is more than 60 mug/influenza virus strain/ml. The ingredients (i) and (ii) can be provided in a form of kit.
