A method of and an apparatus are provided for signaling a transmission code set in data broadcasting. A client using the transmission code set signaling method includes a demultiplexer demultiplexing a packetized elementary stream (PES) packet corresponding to a program selected by a user from the broadcasting stream received by the system interface, an image decoder decoding the demultiplexed PES for images, a sound decoder decoding the demultiplexed PES for sound, and a CPU fetching information about a transmission code set of a character string used in an object carousel message from the demultiplexed message PES and decoding the character string used in the object carousel message based on the fetched information about the transmission code set.