A transmission device configured to transmit, to a reception device, signals including a video signal, the transmission device comprising: a controller configured to • read out information, from the reception device, regarding a video specification that is supported by the reception device, including information regarding a horizontal resolution and a vertical resolution and division ratio information indicating supported frame rates as ratios of a standard frame rate, • generate a pixel clock that matches the read-out horizontal and vertical resolutions, and • generate a TMDS clock through frequency dividing the pixel clock by a division ratio N corresponding to one of the supported frame rates; a transmitter (2b, 2c, 2d) configured to transmit • the video signal, based on a TMDS clock generated by the controller, in a form of baseband video data according to the read-out horizontal resolution and vertical resolution, and • the TMDS clock, wherein when the transmission device is in an output mode in which an identical image is shown for an extended period of time, as in the cases of displaying still images, paused videos of moving pictures, and slow-motion reproduction video of moving pictures, • N is selected to be greater than 1, and • the controller performs a control of multiplexing to the video signal to be transmitted, during a blanking period of the video signal, information indicating the division ratio N. a controller configured to • read out information, from the reception device, regarding a video specification that is supported by the reception device, including information regarding a horizontal resolution and a vertical resolution and division ratio information indicating supported frame rates as ratios of a standard frame rate, • generate a pixel clock that matches the read-out horizontal and vertical resolutions, and • generate a TMDS clock through frequency dividing the pixel clock by a division ratio N corresponding to one of the supported frame rates; • read out information, from the reception device, regarding a video specification that is supported by the reception device, including information regarding a horizontal resolution and a vertical resolution and division ratio information indicating supported frame rates as ratios of a standard frame rate, • generate a pixel clock that matches the read-out horizontal and vertical resolutions, and • generate a TMDS clock through frequency dividing the pixel clock by a division ratio N corresponding to one of the supported frame rates; a transmitter (2b, 2c, 2d) configured to transmit • the video signal, based on a TMDS clock generated by the controller, in a form of baseband video data according to the read-out horizontal resolution and vertical resolution, and • the TMDS clock, • the video signal, based on a TMDS clock generated by the controller, in a form of baseband video data according to the read-out horizontal resolution and vertical resolution, and • the TMDS clock, wherein when the transmission device is in an output mode in which an identical image is shown for an extended period of time, as in the cases of displaying still images, paused videos of moving pictures, and slow-motion reproduction video of moving pictures, • N is selected to be greater than 1, and • the controller performs a control of multiplexing to the video signal to be transmitted, during a blanking period of the video signal, information indicating the division ratio N. • N is selected to be greater than 1, and • the controller performs a control of multiplexing to the video signal to be transmitted, during a blanking period of the video signal, information indicating the division ratio N.