It is an object of the present invention to provide a capacitor-less memory which can prevent a change of a threshold voltage due to flowing out of carriers and improve the memory retention property without a complicated structure. In the capacitor-less memory which uses a transistor, the transistor includes a source region, a drain region, an active layer region which is provided between the source region and the drain region, and a gate electrode which is adjacent to the active layer region with an insulating film interposed therebetween. The source region is formed of a semiconductor having a larger band gap than a band gap of a semiconductor of the active layer region and a band gap of a semiconductor of the drain region, and a heterojunction is formed at the interface between the source region and the active layer region.