1. A tape printing device which is capable of accepting a plurality of different types of tape cartridge, each type of tape cartridge accommodating a printing tape having a printable width distinct from one another, said tape printing device being used for printing data in at least one line on said printing tape while said tape cartridge is set in a tape cartridge holder unit of said printing device, said tape printing device comprising: an input unit which is used to input print data; a display which is capable of displaying an image; a sensor arranged in said tape cartridge holder unit and adapted to detect which type of said tape cartridge is set in said tape cartridge holder unit; and a display control circuit configured to graphically display a layout image of the printing tape and the print data on said display, graphically displaying their locational layout relationship as they will be printed on said printing tape based on the input print data and the type of said tape cartridge detected by said sensor.