A sense amplifier includes an amplifying circuit and a voltage equalizing circuit. The amplifying circuit includes: a first P-type transistor, having a first terminal connected to a third node, a second terminal connected to a first node, and a gate connected to a first bit line; a second P-type transistor, having a first terminal connected to the third node, a second terminal connected to a second node, and a gate connected to a second bit line; a first N-type transistor, having a first terminal connected to the first node, a second terminal connected to a fourth node, and a gate connected to the first bit line; a second N-type transistor, having a first terminal connected to the second node, a second terminal connected to the fourth node, a gate connected to the second bit line. The voltage equalizing circuit is connected between the first node and the second node.