Semiconductor memory device and its program/erase verifying method

PURPOSE: A semiconductor memory device and a method for verifying program/erase on the same are provided to verify the program/erase by using only one circuit. CONSTITUTION: The semiconductor memory device includes a memory cell array(10), an I/O buffer, an input/output buffer(30), a write driver, a detection amplifier(90), a control logic(110) and a verifier(130). The I/O buffer receives data from outside, stores the data and delivers the data to cells. The write driver amplifies the data from the I/O buffer and write the data on the memory cell array. The detection amplifier detects and amplifies the data in the memory cell. The control logic controls the detection of data pass/fail by generating an erase verification control signal and a data delivering signal with response to the detection control signal. The verifier(130) receives the data from the I/O buffer, determines the on/off state of the program and erase cells to determine whether the device is passed or failed. The I/O buffer includes a latch which stores during program verification operation and varies the data stored by the erase cell with response to the data of the erase cell. during erase operation.