MONITOR CIRCUIT, SEMICONDUCTOR INTEGRATED CIRCUIT, SEMICONDUCTOR DEVICE, AND POWER SUPPLY VOLTAGE CONTROL METHOD THEREOF

PROBLEM TO BE SOLVED: To provide a monitor circuit capable of accurately measuring a supply voltage to a functional block.SOLUTION: According to one embodiment, a monitor circuit comprises: a reference voltage generation unit that generates reference voltages Vthsen and Vthref; an amplifying unit OPA1 that amplifies a difference voltage between the reference voltages Vthsen and Vthref; an amplifying unit OPA2 that amplifies a difference voltage between an internal power supply voltage VDD1i, which is supplied to a CPU 101 that is provided in a semiconductor integrated circuit 100, and the reference voltage Vthsen; and a comparing unit CMP1 that performs comparison between amplification results obtained by the amplifying units OPA1 and OPA2, and performs output as a measurement result.