Abstract: An EEPROM capable of arbitrarily setting a write time includes a timer circuit connected to a trimming circuit for determining a write time, and a trimming redundant memory array used for storing trimming data to be supplied to the trimming circuit in accordance with a predetermined write time so that the write time can be arbitrarily set. A series of calibration operations are performed such that the trimming data is read from the trimming redundant memory and supplied to the trimming circuit and the timer circuit is controlled so as to set the write time to a desired value. The latter operation is carried out in parallel to a normal write operation. Accordingly, neither special instructions nor an additional time period are required to perform the calibration operation, and a stable operation can be achieved in less time.