A semiconductor memory device including a substrate having one conductivity type; read only memory element formed in the substrate for storing fixed information, the element having a control gate, a floating gate, a source region, and a drain region, both of the regions having an opposite conductivity type to that of the substrate; a first region having the above one conductivity type which surrounds the element; a light shield layer, connected to the source region and the first region, for covering the element; a second region having the opposite conductivity type which is located outside of the first region for taking out the drain region; and a well region having the opposite conductivity type, the well region linking the drain region and the second region, a part of the first region being formed in the well.