In a D/A converter circuit including a current mirror circuit constructed with an input side transistor circuit and an output side transistor circuit, the input side transistor circuit comprises a series circuit of a first MOS transistor and a second MOS transistor and a first switch circuit connected in parallel to the first MOS transistor. Gates of the first and second MOS transistors are connected commonly and a source of either one of the first and second MOS transistors is connected to a drain of the other of the first and second MOS transistors and the second MOS transistor has a gate length shorter than a gate length of the first MOS transistor.