A semiconductor device that can perform voltage monitoring with a small circuit area is provided. The resistive subdivision circuit RDIV performs the resistive subdivision of the input voltage Vin by means of the input ladder resistor (R1-R4), and drives the nMOS transistors MN1-MN3 by the subdivided input voltages Vi1-Vi3 each having different resistive subdivision ratios, respectively. The pMOS transistor MP0 is provided in common for the pMOS transistors MP1-MP3, and configures a current mirror circuit with each of the pMOS transistors MP1-MP3. The bias current generating circuit IBSG supplies a bias current to the pMOS transistor MP1.