PROBLEM TO BE SOLVED: To provide an expression inhibitor of insulin-like growth factor-binding protein-5 (IGFBP-5) which is expressed in prostate, mammary gland, skin, and hair follicle and is especially related to a hair shape, and an agent for controlling hair shape.SOLUTION: An expression inhibitor of IGFBP-5 and an agent for controlling hair shape contain Swertia japonica of Gentianaceae or its extract as an active ingredient. Since overexpression of IGFBP-5 causes non-straight hair, the expression inhibitor of IGFBP-5 has an effect as the agent for controlling hair shape improving the non-straight hair.