A reference current generating circuit with high current mirror accuracy is provided by low power supply voltage operation. The reference current generating circuit includes a cascode current mirror circuit 1 outputting mirror currents I1 and I2, and a reference current Iref, a current-voltage converter circuit 2 converting the mirror current I1 into a voltage V1, a current-voltage converter circuit 3 converting the mirror current I2 into a voltage V2, a differential amplifier 4 in which the voltage V1 is input to a first input terminal and the voltage V2 is input to a second input terminal, a voltage-current converter circuit 5 converting a voltage V3 output from the differential amplifier 4 into currents I3 and I4, and a current-voltage converter circuit 6 converting the current I3 into a voltage V4 which is output to a gate of a transistor in the cascode current mirror circuit.