Optimum compounding composition of a local injection preparation for treating rectal submucous lesioned abnormal tissue with local anesthetic is decided to provide a medical composition kit. In a composition kit for the treatment where respective containers are unsealed upon being used and respective contents are mixed to obtain a preparation for injection, a medical composition kit which is characterized in that respective single doses of a therapeutic preparation and local anesthetic are fractionally charged in containers, the said therapeutic preparation contains 1.about.10% of a water-soluble aluminum compound and 0.01.about.2% of tannic acid and the said local anesthetic contains 0.1.about.1% of lidocaine hydrochloride or 0.5.about.5% of procaine hydrochloride.