In an embodiment, a bit line sense amplifier of a semiconductor memory device with an open bit line structure includes sense amplifier blocks, first voltage drivers, and a second voltage driver. The sense amplifier blocks include a first sense amplifier and a second sense amplifier, each sensing and amplifying a signal difference between a bit line and a complementary bit line. The first voltage drivers apply a power source voltage to the first sense amplifier, and the second voltage driver applies a ground voltage to the second sense amplifier. The first voltage drivers are disposed for every two or more sense amplifier blocks in a bit line sense amplifier region in which the sense amplifier blocks are arranged, and the second voltage driver is disposed in a conjunction region in which a control circuit is located to control the sense amplifier blocks. Both capacitive noise and device size are minimized.