Considering the dispersion in the access time of semiconductor memories, at least a first and a second memory circuit are connected to the output of a sense amplifier. The output of the sense amplifier is an input to these two memory circuits alternatively at different timings. The data stored in these memory circuits are alternately transferred to a data output circuit. Even when the access time becomes long, the desired sense data can be successively read out from the output of the data output circuit at a short time interval determined by the clock cycle. When the access time becomes short and even when a second data is generated from the output of the sense amplifier at the timing of transferring a first data in the first memory circuit to the data output circuit, the first data held in the first memory circuit is prevented from being renewed by the second data. In this case too, the desired sense data can be successively read out from the output of the data output circuit at a time interval determined by the clock cycle.