PURPOSE: A buffer amplifier is provided to stabilize electrical properties in a change in PVT conditions by decreasing a change in a voltage gain through a big input impedance and a small output impedance. CONSTITUTION: A bias supply part(110) supplies bias power with a voltage level that has been established in advance. An amplification unit(120) amplifies an input signal by respectively being supplied with the bias power from the bias supplier and the driving power which were established in advance. A compensation unit(130) compensates for a current unbalance in the driving power supplied to the amplification unit. The bias power comprises a first bias power which has a voltage level established beforehand and a second bias power which has a voltage level that is higher than that of the first bias power.
