The present invention relates to a method of providing an early media service based on a session initiation protocol (SIP), wherein early media of a multimedia form can be provided under SIP-based B2BUA mode operation. According to the present invention, in a case where early media are provided to an originating terminal when a call connection with a terminating terminal is established at the request of the originating terminal, the early media is provided in the form of multimedia data, such as text, image, moving image, flash animation and the like, as well as audio data, and thus users desires are fulfilled and users satisfactions are maximized. In addition, with individual operation management of the terminating terminal and the originating terminal according to B2BUA mode operation based on the session initiation protocol and an early session initiation with the originating terminal, an early media service can be normally provided to the originating terminal even when the terminating terminal is in an abnormal operation state.