A semiconductor memory comprises a first cell (memory cell) including a charge storage layer, and a second cell including a charge storage layer and used with its set threshold value fixed. The threshold value of the second cell is generally apt to return to the initial state, i.e., initial threshold value, when damaged by baking. So, the initial threshold value is shifted to approach the threshold value to be set, as closely as possible. The data retention characteristic of the second cell (reference cell, redundancy memory cell, or OTP region cell) formed into the same construction in the same process as the first cell, can be considerably improved without unnecessarily increasing steps of manufacturing process.