1. A message security processing system for Web services in which messages are exchanged between a client and a server with a SOAP-Remote Procedure Call (RPC) format, each of the client and the server comprising: a security interface to allow security information related to digital signature, encryption, and timestamp insertion to be set by an application program in a security context object to meet security requirements of the client or the server, a security handler to receive the security context object from the security interface, and to perform security processing of a request message by calling security objects stored in a request queue of the security context object one by one in order and performing security processing of a response message by calling security objects stored in a response queue of the security context object one by one in order; and an XML security unit to support an XML security function called by the security handler, wherein, after the security context object is received by the security handler, the application program performs a SOAP-RPC to exchange the message which is secured by the security handler, between the client and the server, without generating a SOAP message by the application program, wherein the security context object is separate from the messages exchanged between the client and the server using the SOAP-RPC format.