A memory device includes a first data strobe pad; a strobe signal generation circuit suitable for generating a read data strobe signal based on a read timing signal; a monitoring receiver suitable for receiving the read data strobe signal fed back through the first data strobe pad according to a monitoring enable signal; a sampler suitable for generating a sampling clock by sampling the fed back read data strobe signal according to a random clock; a first counter suitable for generating a first counting signal by counting the random clock; a second counter suitable for generating a second counting signal by counting the sampling clock; and a duty detector suitable for generating a duty ratio detection signal based on the first counting signal and the second counting signal.