A nonvolatile memory device includes one or more reference cell transistors, one or more memory cell transistors, and a current source circuit including three or more field effect transistors that have gates thereof connected together, the three or more field effect transistors including two or more field effect transistors and another field effect transistor, currents flowing through the two or more field effect transistors being combined to flow through the one or more reference cell transistors, and another field effect transistor having a drain thereof connected to one of the one or more memory cell transistors.