A flash memory device and a method of testing the flash memory device are provided. The flash memory device may include a memory cell array including a plurality of bit lines, a control unit configured to output estimated data and an input/output buffer unit including a plurality of page buffers. Each of the plurality of page buffers corresponds to one of the plurality of bit lines in the memory cell array and is configured to read test data programmed in at least a first page of a memory cell array, compare the read-out test data with the estimated data to determine whether the corresponding bit line is in a pass or failure state and output a test result signal. A voltage of the test result signal is maintained when test data of a second page of the memory cell array is read if the corresponding bit line in the first page is in a failure state.