A semiconductor storage device has a single gate electrode formed on a semiconductor substrate through a gate insulation film. First and second memory function bodies formed on both sides of the gate electrode. A P-type channel region is formed in a surface of the substrate on the side of the gate electrode. N-type first and second diffusion regions are formed on both sides of the channel region. The channel region is composed of an offset region located under the first and second memory function bodies and a gate electrode beneath region located under the gate electrode. The concentration of a dopant which imparts a P-type conductivity to the offset region is effectively lower than the concentration of a dopant which imparts the P-type conductivity to the gate electrode beneath region. This makes it possible to provide the semiconductor storage device which is easily shrunk in scale.