There is provided a linear amplifier capable of suppressing a reduction in bandwidth and reducing a ripple voltage by using a source follower and a local feedback loop. The linear amplifier includes an amplifier amplifying an input signal according to a difference in signal level between the input signal and a feedback signal, and a buffer buffering a signal amplified in the amplifier by a source follow method, suppressing a reduction in bandwidth of the signal, outputting the signal, and providing the bufferred signal to the amplifier as the feedback signal.