A vector for creating kf-1 gene knockout nonhuman animals exhibiting increased anxiety-like behaviors, and containing Lox-pM-M-kf-1[in3b]-kf-1[ex4a]-LoxP, (wherein, M is a selection marker gene, pM is a promoter for the expression of the selection marker gene, kf-1[in3b] is a sequence represented by SEQ ID NO: 2, and kf-1[ex4a] is a sequence represented by SEQ ID NO: 3); kf-1 gene knockout nonhuman animals exhibiting increased anxiety-like behaviors produced by using the vector or a descendant of the animal, and a method for use of the same.