Therapeutic or prophylactic agent for itching skin diseases

Disclosed is a novel means whereby itching skin diseases such as atopic dermatitis can be treated or prevented. The present inventors conducted extensive studies and consequently found that antibacterial peptide LL-37 has an effect of promoting the expression of nerve repulsion factor Sema3A, etc. LL-37 is a peptide consisting of 37 residues at the C-terminus of human cathelicidin hCAP18. By using this antibacterial peptide, the expression of an axon guidance molecule such as a nerve repulsion factor can be normalized in a lesion of an itching skin disease such as atopic dermatitis or xeroderma and thus itching can be reduced and the skin lesion can be ameliorated.