According to an embodiment of the present disclosure, a semiconductor memory device includes a mode register circuit including a plurality of write mode register sets for providing a plurality of setting codes or a plurality of monitoring codes; and a defect detection circuit suitable for outputting a defect determination signal by detecting any defect in the mode register circuit, based on the plurality of monitoring codes, wherein each of the write mode register sets includes: a storing circuit suitable for storing an operational code according to a mode register write command; and an output control circuit suitable for outputting the stored operational code in the storing circuit as a corresponding setting code, or inverting the stored operational code in the storing circuit to output a corresponding monitoring code, according to a test mode signal.