Abstract: A plurality of signal display lamps 1A to 1E are communicably connected together through a network 3. Each of the signal display lamps 1A to 1E includes a display portion 12 capable of performing a variable display. Each of the signal display lamps 1A to 1E is capable of performing a mirroring operation in addition to being capable of performing a variable display in the display portion 12 in response to an input signal that is input from input signal lines 8A to 8E. For example, in the signal display lamp 1A, any of the signal display lamps 1B to 1E is selected, and its display state can be simulated. Each of the mirroring source signal display lamps 1B to 1E can be selected by giving a selective command signal from a selective-command-signal generating device 60 connected to the input signal line 8 of the signal display lamp 1A.