1. An apparatus for transmitting a stereoscopic image packet, the apparatus comprising; a stereoscopic packet generator which generates a stereoscopic image packet using a stereoscopic packet header, a stereoscopic video packet header, and a payload; and a transmitter which transmits the stereoscopic image packet; wherein the stereoscopic packet header and the stereoscopic video packet header are formed so that the stereoscopic packet header and the stereoscopic video packet header are not dependent on a particular transport protocol, the stereoscopic packet header comprises additional information required for playback of stereoscopic image data existing in the payload, and the stereoscopic video packet header comprises attribute information of the stereoscopic image data in the payload, wherein the attribute information comprises decoding information and a time-stamp needed for a decoding operation, and wherein the additional information is transmitted based on associated flags only in packets including Instantaneous Decoding Refresh (IDR) pictures of video data to process stereoscopic image data related to the additional information, and the stereoscopic packet header periodically transmits information applied to an entire sequence of the stereoscopic image data.