When a time code signal corresponding to an image signal, to which a format conversion changing the number of frames per second is executed, is transmitted, information indicating a frame position where image data is changed through the format conversion in the image signal is attached to the time code signal to be transmitted. Alternatively, information indicating a synchronous state between frame conversion cycles in the format conversion and time code progression is attached to the time code signal. In the foregoing manner, a relationship between the frame position and the time code can be accurately grasped. Further, a secondary conversion (inverse conversion) is accurately executed to the image signal by means of the time code signal.