PROBLEM TO BE SOLVED: To provide a lactobacillus-cocultivated extract extracted by cultivating a lactobacillus group which can contribute to the inhibition of influenza and the inhibition of the disease caused by influenza.SOLUTION: The extract extracted by cultivating a lactobacillus group respectively includes: biotin (vitamin H) by 3.3 to 4.1 ng (ng/ml) in the extract of 1 ml; sphingomyelin by 0.18 to 0.22 mg (mg/ml) in the extract of 1 ml; and vitamin B12 by 140.0 to 171.6 pg (pg/ml) in the extract of 1 ml.