Structural countersignature involving multiple agencies is common in the application of electronic government. However, most countersignature schemes are sequence signature schemes which can not apply to the complicated structure of countersignatures. In the scheme, a semi-trusted third party is in charge of the transmission of original electronic documents and the signatures of indirect precursor agencies and the generation of the public keys, each agency must verify the signatures of all of his precursor agencies and his signature must be verified by all of his successor agencies too. In the scheme, the computation cost of the algorithm to generate a signature is proportional to number of the agencies and the verification cost of the final signature is as same as a single RSA signature. After the verifications of the signatures between the agencies passed, no agency can deny his signature.