A reference current generating circuit includes an operational amplifier having one input terminal to receive a reference voltage and a field effect transistor having a gate to receive an output voltage of the operational amplifier. k resistors (k is an integer not less than 2) are connected in series to a drain of the field effect transistor, and a voltage at one of connection points of the resistors is feed backed to the other input terminal of the operational amplifier. A switch selects one of the connection points of the resistors and applies the voltage of the selected connection point as a reference voltage to a gate of a reference transistor to generate a reference current.