Provided are a method and an apparatus for transmitting metadata in a WFD. More particularly, a WFD source transmits, to a WFD sink, a first transmission stream in which an audio stream and a video stream are superimposed and multiplexed. The WFD source receives, from the WFD sink, a first RTSP request message for requesting transmission of metadata for audio data and video data during the transmission of the first transmission stream. The WFD source transmits, to the WFD sink, a first RTSP response message in response to the first RTSP request message during the transmission of the first transmission stream. The WFD source transmits, to the WFD sink, a metadata stream including the metadata and a second transmission stream in which the audio stream and the video stream are superimposed and multiplexed.