Abstract: A video signal selection circuit capable of reading automatically the connection state of a plurality of video jack ports and selecting only modes corresponding to video ports which presently have a jack connected thereto. This video signal selection circuit includes a predetermined number of video jack ports, a predetermined number of switches respectively connected to the video jack ports and turned on when a corresponding jack is connected to the video jack port, and a micro-processor which registers the fact that the jack is connected to the video jack port by checking whether the corresponding switch is turned on. The micro-processor outputs a control signal so that the selection circuit selects only those ports to which jacks are connected when a mode conversion key is actuated. A switching portion is controlled by the micro-processor's control signal and selects for output only those video signal sources corresponding to the control signals received from the micro-processor.