To obtain a voltage detector circuit capable of immediately measuring a detection voltage by adding a simple circuit upon input of a specified test signal, thereby greatly reducing the required time for measuring the detection voltage.

When a test signal St at high level is inputted to a test signal input terminal 13 at a test mode, an input switching circuit 5 inputs an output signal from an operational amplifier 4 to an input end IN of a voltage divider circuit 3, instead of an input voltage Vi inputted from an input terminal 13, to measure an output voltage Vo from the operational amplifier 4 so that fuses HU1-HU9 of the divider circuit 3 are selectively blown off according to the measurement result.