PURPOSE: To adjust separately P-channel and N-channel transistors(TRs) of the dimension of the final stage of an output buffer by adopting the constitution such that the final stage N-channel and P-channel TRs, plural pre-stages controlling the TRs separately and plural control gates inputting to the pre-stage are provided.

CONSTITUTION: CMOS TRs are adopted for the final stage TRs 11, 12 and a source of a P-channel TR connects to a power supply and a source of an N-channel TR connects to GND. The load capacitor 15 is driven by the TRs. A buffer 13 connects to each gate of the final stage TRs 11, 12. An output control logic gate 14 is controlled by output control signals 16, 17 and outputs a data signal 18.