this invention relates to a semiconductor memory having a high speed operation and a high integration density . when a high integration semiconductor memory is applied to a large scale computer system , storage data must be erased at a high speed for data security . the present invention erases the storage data by a method which is different from the write method of conventional prior art . in the invention , the erasing operation is made by continuously selecting word lines while sense amplifiers are kept in this on - state . the present invention includes a control circuit for attaining such an operation , and can be used for a semiconductor memory implemented in a computer system accessed by a plurality of users .