A semiconductor storage device includes a plurality of memory elements and a redundancy circuit. Each of the memory elements includes a gate electrode provided on a semiconductor layer, a gate insulating film intervening between the gate electrode and the semiconductor layer, a channel region provided under the gate electrode, diffusion regions respectively provided at both sides of the channel region, the diffusion regions having a conductivity type which is opposite a conductivity type of the channel region, and memory functioning members respectively provided at both sides of the gate electrode, the memory functioning members having a function of holding charge. The redundancy circuit addresses a single chip memory including cells associated with a plurality of redundant lines and includes a decoder for selecting a redundant row. The semiconductor storage device can permanently inactivate further programming of the redundancy circuit in order to prevent a user from performing inadvertent programming.