The present invention relates to a pharmaceutical composition, food composition and cosmetic composition for preventing, treating, or improving allergic diseases comprising extract or fraction of a plant of the Justicia genus as an active ingredient. The extract or a fraction of a plant of the Justicia genus according to the present invention can inhibit IgE antibody secretion and the degranulation of mast cells and basophils, and exhibits an excellent anti-allergic effect, and thus can effectively prevent, treat, or improve allergic diseases.
