To provide a semiconductor storage device wherein, without preventing realing higher density for a memory cell, stable read-out operation is performed to a memory cell array of large variation in threshold after erasing.

In a reading-out operation, when a word line WL (0) is selected with positive selection electric potential (VCC), a source line SL (0) connected to a selected memory cell is taken as a ground electric potential, only a word line WL (1) connected to a selected memory cell and a memory cell sharing a source is taken a negative non-selected electric potential (-VG1), with other word line taken as a ground electric potential, and a source line of a memory cell connected to the other word line is taken as being open. Thereby, supply of negative voltage is only to the word line WL (1), so that as a negative voltage generating circuit it can be of a small scale, thus even when a memory cell having a threshold value of 0V or less at a non-selected memory cell is present, no leak current flows in a bit line, enabling normal reading-out operation.