The present invention creates a SOAP message without using DOM by generating a body part by sequentially performing such a process of a message as encryption or signing for each piece of the message, generating a header part by using information acquired during the process, and by combining the body part and the header part. The present invention also breaks a SOAP message without using DOM by acquiring header information with parsing a received SOAP message and sequentially performing decode or verification of a signature of a body part according to the header information.