THE PRESENT INVENTION AIMS TO PROVIDE A FREEZE-DRIED PREPARATION IN WHICH THE INFLUENZA VACCINE EXHIBITS IMPROVED STABILITY. A FREEZE-DRIED PREPARATION IN WHICH THE INFLUENZA VACCINE EXHIBITS SIGNIFICANTLY IMPROVED STABILITY CAN BE OBTAINED BY FREEZE-DRYING AN AQUEOUS SOLUTION THAT MEETS THE FOLLOWING CONDITIONS (A) TO (C): (A) (I) AN INFLUENZA VACCINE, (II) A HYDROPHOBIC AMINO ACID, AND (III) ARGININE AND AN ACID ADDITION SALT THEREOF ARE INCORPORATED (B) THE PROPORTION OF THE COMPONENT (III) IS FROM 20 TO 85% BY WEIGHT RELATIVE TO THE TOTAL AMOUNT OF THE RESULTING FREEZE-DRIED PREPARATION AND (C) THE pH IS ADJUSTED TO BE FROM 8 TO 10 BY CONTROLLING THE PROPORTION OF ARGININE AND AN ACID ADDITION SALT THEREOF THAT FORM THE COMPONENT (III).
