An apparatus of transmitting stereoscopic image data includes an image data output unit configured to output stereoscopic image data including left-eye image data and right-eye image data about a certain program; and an image data transmitting unit configured to transmit a transport stream including the stereoscopic image data about the certain program output from the image data output unit. The image data transmitting unit incorporates identification information indicating whether disparity data is transmitted in the transport stream. The disparity data is used to add disparity to superimposed information to be superimposed on an image generated from the left-eye image data and the right-eye image data.