Disclosed is a security system of a call signaling message. An object of the invention is to provide a security system and a securing method of a call signaling message, in which even when a call signaling message is leaked out and thus modified in a SIP (Session Initiation Protocol) based VoIP (Voice Over Internet Protocol) service, the modified message is blocked in advance to enable the VoIP service to be provided without an attack effect by the packets. When using the security system and the securing method of a call signaling message according to an embodiment of the invention, it is possible to prevent, in the SIP based VoIP service, a call signaling message from being modified to cause a call failure when requesting a call or during the call, and to block an attack on the call signaling message in advance.