In one aspect, a semiconductor memory device includes a plurality of phase-change memory cells which are programmed according to a write current applied to the phase-change memory cells, a voltage boosting circuit which receives a first voltage and outputs a boosted voltage which is greater than the first voltage, and a write driver which receives the boosted voltage and which generates the write current from the boosted voltage. In another aspect, the write driver generates the write current corresponding to one of a set current pulse and a reset current pulse, and at least one of the set current pulse and the reset current pulse is gradually increased.