Disclosed is a television signal processing apparatus in which a picture signal having a high resolution can be broadcast while maintaining compatibility with the conventional broadcast systems and ensuring developability of the conventional mode of broadcasting and according to which multiple broadcast programs can be simultaneously broadcast. For this purpose, the known letter box method is used to transmit the main panel part of a picture, and a novel method is used to transmit the remaining bar parts of the picture by a path of transmission through a bar signal processor unit (4) and a path of transmission through a quadrature modulator unit (7) provided for quadrature modulation of the video carrier. Further, various devices are provided for the purpose of future development. According to a first stage of the present invention using the above means, both the conventional mode of analog modulation and a new mode of modulation such as digital modulation are made in the same channel for broadcasting the same program, thereby providing a television receiver conforming to the new modulation mode and satisfying the new mode of picture display. According to a second aspect, the conventional analog modulation system is replaced by a new modulation system so as to transmit a high definition picture signal, so that the receiver can reproduce the picture having a very high degree of definition. Also, because the picture can be efficiently transmitted by the new mode of modulation, the high definition picture can be transmitted in the same frequency band, and the shift from the conventional system can be attained while maintaining compatibility. Further, multiple broadcast programs of conventional pictures can be efficiently transmitted.