PROBLEM TO BE SOLVED: To provide a technique which can improve effectively and simply swelling of lower limbs.SOLUTION: A instrument for improving swelling includes a vapor warming tool 1 that includes a water vapor generating unit using heat evolution by oxidation reaction of oxidizable metal and gives water vapor to the skin, and a supporter 2 that is used for holding and fixing the vapor warming tool 1 and is formed of a cylindrical body with both ends opened. The vapor warming tool 1 contains menthol, and has tensile strength of 2-25 N/50 mm produced when the supporter 2 is elongated in circumferential direction by 300%.