A bit memory circuit of an antifuse element set includes two antifuse elements of which logical states are changed from an insulation state to a conductive state when a program voltage is applied. 1-bit data is represented by the logical states of the two antifuse elements. The two antifuse elements are collectively controlled by one decoder circuit. When writing data, the decoder circuit simultaneously performs insulation-breakdown on the two antifuse elements by simultaneously connecting the two antifuse elements to program voltage lines, respectively.