Source/drain regions of an MOS transistor are formed at a surface of a p-type silicon substrate. A storage node electrically connected to the source/drain regions penetrates a bit line to reach the n-type source/drain region. The storage node and the bit line are insulated from each other by a sidewall insulating layer. Thus, a semiconductor memory device suitable for high integration is obtained in which short-circuit between the storage node and the bit line on a gate electrode layer can be prevented.