To screen a readout reliability defect which is caused by a defect of insulation characteristics due to a defect at ferroelectric film formation time at the time of an initial inspection.

The time from the activation of a cell plate line signal (CP) to the activation of a sense amplifier signal (SA) is set longer at inspection time than at normal time. Consequently, the mentioned time is set much longer than the time constant of the RC product of a resistance component generated owing to the insulation characteristic defect and the capacity of a bit line, variation in bit line potential due to a leak can be detected by a sense amplifier at the inspection time, and the reliability defect having the resistance component can be detected as a defect in the beginning.