Abstract: The invention performs an accurate testing in order to determine the presence or absence of a defect in a wiring and electrodes in an electro-optical device. A test method is provided for testing an electro-optical device that includes a capacitor arranged at an intersection of each scanning line and each data line. A test switching element connected between the data line and a reading signal-line is turned on after storing a charge responsive to a data signal in the capacitor so that the voltage responsive to the charge stored in the capacitor is output to the reading signal-line. The timing of switching on the test switching element is set to be different from the timing of a level change of a test clock pulse that defines the operation of a test circuit.