A non-volatile semiconductor memory device includes a memory cell array having electrically erasable and programmable non-volatile memory cells, a part of the memory cell array being defined as a initial set-up data region for storing a plurality of initial set-up data that define memory operation conditions, data latch circuits for holding the initial set-up data read out from the initial set-up data region, a controller for controlling data program and erase operations for the memory cell array, and a clock generator for generating a clock signal that is used to define an operation timing of the controller, wherein the controller is configured to perform such an initial set-up operation that sequentially reads out the plurality of initial set-up data stored in the initial set-up data region and transfers them to the respective data latch circuits on receipt of power-on or a command input, the initial set-up operation being so performed as to read out a clock cycle adjustment data within the plurality of initial set-up data stored in the initial set-up data region in the beginning, thereby adjusting a clock cycle of the clock signal output from the clock generator by use of the clock cycle adjustment data, and then reads out the remaining initial set-up data by use of the adjusted clock signal.