A voltage dropping circuit generating a second power source voltage to output to a second node by dropping a first power source voltage supplied to a first node, includes: an output transistor having a first terminal to which the first power source voltage is supplied and a second terminal connected to the second node turns on or off according to a difference between the second power source voltage and a reference voltage; and a back gate variable diode circuit including a diode-connected transistor connected between the first node and the first terminal and to configured to turn on or off according to a voltage difference between the first and second power sources, wherein the first power source voltage is applied to the back gate of the diode-connected transistor when it is higher than the second power source voltage, and the second power source voltage is applied in other case.