An internal signal generator for use in a semiconductor memory device includes an internal read address generation unit and an internal write address generation unit. The internal read address generation unit generates a plurality of read delay addresses by delaying an external address for a predetermined latency shorter than an additive latency set by the semiconductor memory device and selects one of the read delay addresses to thereby output an internal read address. The internal write address generation unit generates a plurality of write delay addresses by delaying the internal read address for a preset latency shorter than a column address strobe (CAS) latency set by the semiconductor memory device and selects one of the write delay addresses to thereby output an internal write address.