A medical composition kit for treating rectal submucous lesioned abnormal tissue wherein respective containers are unsealed upon being used and respective contents are mixed to obtain a preparation for injection, characterized in that respective single doses of a therapeutic preparation and an agent for local anesthesia are separately packed in containers, the therapeutic preparation contains 1 to 10 % of a water-soluble aluminum compound and 0.01 to 2 % of tannic acid and the agent for local anesthesia contains 0.1 to 1 % of lidocaine hydrochloride or 0.5 to 5 % of procaine hydrochloride. The kit has an optimum compounding ratio between a therapeutic preparation and an agent for local anesthesia.