PROBLEM TO BE SOLVED: To provide a reliable nonvolatile semiconductor memory device capable of reducing stress in the tunnel oxide film of a memory cell in writing and erasuring. SOLUTION: In a write state machine circuit 3 for controlling a program circuit 4 and an erasing circuit 5, first and second synchronous signals are used. In the first synchronous signal, an oscillation period from an oscillator circuit 1 for programs has negative temperature characteristics. In the second synchronous signal, an oscillation period from an oscillator circuit 2 for erasing has positive temperature characteristics. The width of a write pulse in the program circuit 4 controlled by the write state machine circuit 3 is nearly proportional to the oscillation period of the first synchronous signal in the oscillator circuit 1 for programs. Contrarily, the width of an erasing pulse in the erasing circuit 5 controlled by the write state machine circuit 3 is nearly proportional to the oscillation period of the second synchronous signal in the oscillator circuit 2 for erasing. COPYRIGHT: (C)2005,JPO&NCIPI