To provide a display control and line terminal control device of a betting ticket selling and refunding business system and a host computer which can be reduced in number of communication lines between an off-cource system and a home system so as to reduce the running cost.

The off-cource system is provided with the display control and line terminal control device 5 for controlling the betting refunding data communication between the host computer 1 and the selling and refunding terminal of the off-cource system and the display data communication from the host computer 1 in the same line. The host computer 1 is provided with a control means for performing refunding data communication of a race with priority over the display data communication just before the race deadline in which selling and refunding data communication is busy. The host computer 1 is provided with a communication frequency control means for controlling the communication frequency of display data and selling and refunding data according to the number of selling and refunding data generated from the selling and refunding terminal of the off-cource system.