An HDMI® source determines whether or not an HDMI® sink can receive a sub-signal based on VSDB of E-EDID. When the HDMI® sink can receive the sub-signal, the HDMI® source adds a sub-signal to pixel data of a main image composed of pixel data whose number of bits is smaller than that of transmission pixel data transmitted by a transmitter, thereby constructing transmission pixel data. This data is transmitted by the transmitter through TMDS channels #0 to #2. Furthermore, the HDMI® source transmits a general control packet containing sub-signal information indicating whether or not the sub-signal is contained in the transmission pixel data in the control period of a vertical blanking period. The present invention can be applied to, for example, HDMI®.