Disclosed is a lyophilized preparation improved in the stability of an influenza vaccine contained therein. A lyophilized preparation remarkably improved in the stability of an influenza vaccine contained therein can be prepared by lyophilizing an aqueous solution satisfying the following requirements (A) to (C): (A) the aqueous solution contains (i) an influenza vaccine, (ii) a hydrophobic amino acid, and (iii) arginine and an acid addition salt thereof (B) the component (iii) is contained in an amount of 20 to 85% by weight relative to the total amount of the lyophilized preparation and (C) the pH value of the aqueous solution aqueous solution is adjusted to pH 8 to 10 by controlling the ratio between arginine and the acid addition salt thereof which constitute the component (iii).
