A memory device including a self-test circuit, a memory cell array, a power voltage generator, and a redundant row address replacement circuit is provided. The self-test circuit is configured to generate a self-test data signal and a power voltage control signal. The memory cell array receives the self-test data signal and outputs a self-test failure signal. The power voltage generator generates a word line power voltage according to a power voltage control signal. The redundant row address replacement circuit receives the word line power voltage and the self-test failure signal to provide a redundant word line address to the memory cell array. The power voltage generator is configured to provide the word line power voltage in a built-in self-test (BIST) mode to be lower than the word line power voltage in a normal mode.