In a liquid crystal display device it is desirable to test in the state of TFT substrates, without reducing the number of TFT substrates to be obtained from one mother TFT substrate, and without increasing the overall size of the TFT substrates. Test terminals are formed on the outside of terminals for driving the liquid crystal display device. The test terminals of the specific TFT substrate are formed in another TFT substrate just below the specific TFT substrate. The area in which the test lines are formed is a space in which a sealing material is formed, between the display area and an end of the lower TFT substrate. Thus, the size of the TFT substrates is not actually increased. A test line area is not separately formed and not discarded, so that the number of TFT substrates to be obtained from one mother TFT substrate is not reduced.