A display device is configured to provide a crack detection line running from a first crack detection terminal along a side of a TFT substrate to extend to a second crack detection terminal. A switching transistor for switching between an image display and crack detection is provided at a side opposite a terminal portion between the crack detection line and a video signal line. The crack that may cause disconnection in the crack detection line is detected by turning the switching transistor on, and applying the voltage for lighting inspection to the first crack detection terminal and the second crack detection terminal sequentially in this order.