A display device capable of permitting a plurality of display units connected together to carry out a series of displays through a single control section, to thereby automatically assign numbers to the display units. The control section and first- to six-stage display units are cascade-connected to each other, wherein the sixth- or last-stage module is connected at an output terminal thereof to an input terminal of the control section. The control section outputs an H signal in synchronism with the trigger signal of which the number of times of outputting is predetermined. The modules each normally outputs the L signal. However, the module outputs the H signal at a timing of the next trigger signal when it is fed with the H signal. Addition of 1 to the number of L signals in each of the modules at the time of N=6 permits a number of the module to be obtained. The control section grasps the number of modules connected based on the number of L signals input thereto.