A comparator circuit, includes a first power source terminal having a first potential, a second power source terminal having a second potential different from the first potential, a detection voltage terminal, a reference voltage generator coupled between the first power source terminal and the second power source terminal, the reference voltage generator generating a middle potential which is a potential between the first potential and the second potential and outputting the middle potential at a middle potential node, the reference voltage generator further generating a reference voltage, a bias unit coupled between the first power source terminal and the middle potential node, the bias unit receiving the reference voltage and generating a corresponding reference voltage by using the first potential and the middle potential as energy sources thereof, and a comparator unit coupled between the first and second power source terminals and the detection voltage terminal.