1. A method for driving a semiconductor memory including a ferroelectric capacitor for storing a multi-valued data in accordance with a displacement of polarization of a ferroelectric film thereof and detection means connected to a first electrode corresponding to one of an upper electrode and a lower electrode of said ferroelectric capacitor for detecting the displacement of the polarization of said ferroelectric film, comprising: a first step of reading said multi-valued data by detecting the displacement of the polarization of said ferroelectric film by said detection means with a reading voltage applied to a second electrode corresponding to the other of said upper electrode and said lower electrode of said ferroelectric capacitor; and a second step of removing said reading voltage applied to said second electrode, wherein said reading voltage applied in the first step has such magnitude that the displacement of the polarization of said ferroelectric film is restored to that obtained before reading said multi-valued data by removing said reading voltage in the second step.