A non-volatile semiconductor memory device includes a current source providing a reference current to a first node and a clamp circuit. The clamp circuit includes a transistor having a current path between the first node and a second node, and an amplifier circuit having a first input port at which a cell reference voltage can be received, a second input port connected to the second node, and an output port connected to a control terminal of the transistor. The amplifier circuit is configured to output a differentially amplified signal from the output port. A memory cell is connected between a bit line and a word line and includes a variable resistance element. The bit line can be connected to the second node. A sense amplifier is connected to the first node to detect data stored in the memory cell.