In this paper, we propose a method of reducing the insertion amount of data at the time of sanitization in order to increase the usefulness of the sanitizable signature scheme for SMF. When a user plays back a part of an SMF, which is signed with a general digital signature, the signature is destroyed. We propose a sanitizable signature scheme for SMF, and the user can prove that a partial playback satisfies the intention of the copyright holder, making it possible to show using the musical piece correctly. With the existing method, the signing object is a hash value set. Therefore, in order to verify the SMF and the sanitized digital signature, all the hash values of the sanitized block are required. With the proposed method, a root hash value is signed instead of a hash value set. Therefore all low rank nodes become a part of the host node, which is a sanitization block, which makes it possible to decrease the insertion amount of data at the time of sanitization of the number of the hash value which a sanitizer inserts.