To realize a MOS buffer circuit which has a simple constitution and is easily made into an integrated circuit and has a noise elimination function.

An input signal is directly supplied to respective gates of a PMOS 3-1 and an NMOS 4-2, and the input signal is supplied to respective gates of a PMOS 3-2 and an NMOS 4-1 after being delayed by a delay element 2. In the period when a spike noise having the pulse width within the delay time of this delay element 2 exists, three out of four transistors are certainly turned off, and therefore, an output 5 goes to the high impedance state, and the just preceding output level is kept, and as the result, the noise is masked.