To obtain a ferroelectric storage device in which a sufficient margin can be ensured between a reference potential and the high level or the low level of a bit line even when the high level and the low level are irregular depending on the position of a chip formed inside a wafer and which can prevent data from being read out erroneously.

In a ferroelectric storage device, a high level and a low level which correspond to the direction of the polarization of a ferroelectric film are read out to a bit line, a reference potential is applied to a bit line, for reference, which forms a pair with the bit line, the potential of the bit line is compared with the reference potential of the bit line for reference, and stored data is sensed and rewritten. In this case, means 105, 111, 112 by which a reference potential is set among from a plurality of voltage levels according to the high level and the low level of the bit line are installed. Since the reference potential is variable, the reference potential which is optimum can be applied even when the characteristic of a ferroelectric capacitor is irregular.