A current mirror circuit includes: a reference current circuit including a reference transistor and a constant current source coupled between a high potential source and a low potential source; a first proportional current circuit, including a first transistor that forms a first current mirror circuit with the reference transistor, to generate a first current having a first ratio to a reference current of the reference current circuit; a second proportional current circuit, including a second transistor that forms a second current mirror circuit with the reference transistor, to generate a second current having a second ratio to the reference current; a comparison circuit to output a difference between a drain voltage of the first transistor and a drain voltage of the second transistor; and a current adjustment transistor coupled to a drain of the second transistor and including a gate to which an output of the comparison circuit is applied.