To provide a method and device for testing the size and conductivity of a foreign material adhered to a substrate for a liquid crystal display device, there is provided a method of testing whether a foreign material including a metal element is adhered to a substrate for a liquid crystal display device, the method including a first test step of detecting the size and position of the foreign material adhered to the substrate and a next step of testing whether the foreign material includes the metal element at the position detected in the first test step.