A broadcast transmitter, a broadcast receiver, and a 3D video data processing method are disclosed. A 3D video data processing method includes processing, by a video formatter, 3D video data, encoding, by an encoder, 3D video data, generating, by a system information processor, system information having 3D video composition information including information about the processing and encoding of 3D video data, multiplexing, by a multiplexer, the system information and the 3D video data, and transmitting, by a transmitter, a broadcast signal. In a 3D video data processing method, a receiver receives a broadcast signal including 3D video data and system information, a system information processor obtains 3D video composition information by parsing the system information, a decoder decodes the 3D video data according to the 3D video composition information, and an output formatter formats and outputs the decoded 3D video data according to the 3D video composition information.