A sense amplifier according to an example of the present invention has first, second, third and fourth FETs with a flip-flop connection. A drain of a fifth FET is connected to a first input node, and its source is connected to a power source node. A drain of a sixth FET is connected to a second input node, and its source is connected to the power source node. A sense operation is started by charging a first output node from the first input node with a first current and by charging a second output node from the second input node with a second current. The fifth and sixth FET are turned on after starting the sense operation.