PURPOSE: A sense amplifier circuit is provided to perform a stable program verifying operation by connecting a reference cell for verifying a program and an erasing state of a flash EEPROM cell to a depletion transistor for maintaining a constant current with a main memory cell. CONSTITUTION: A first resistor(R11) and a main memory cell(M11) are connected between a power terminal(Vcc) and a ground terminal(Vss) in serial. A main control gate voltage(Vcg_main) is provided to the main memory cell(M11) for driving the main memory cell(M11). A second resistor(R12) and a reference memory cell(M12) are connected between the power terminal(Vcc) and the ground terminal(Vss) in serial. A reference control gate voltage(Vcg_ref) is provided to the reference memory cell(M12) for driving the reference memory cell(M12). A sense amplifier(11) senses a voltage of a first node(K11) and a voltage of a second node(K2) and outputs the sensed voltage to an output terminal(Dout). A depletion transistor(N1) for receiving a control voltage(Vdep) is connected between the second node(K2) and the ground terminal(Vss).
