Provided is a small-area one-time programmable semiconductor memory device that uses a PNPN structure, which is parasitically generated in a CMOS process. An N-type region provided in a location other than both ends or a P-type region provided in a location other than both the ends is put into a floating state so that PNPN current flows, and a thermal breakdown of a resistor caused by this current is used as a memory element.