An analog buffer circuit which has small input and output offsets and reduced power consumption even if it is formed on an insulating substrate by TFTs, a display device which uses the analog buffer circuit as a peripheral driving circuit for a display unit, and a portable terminal in which the display device is provided as a screen display unit are provided. By performing offset detection on a source follower in such a manner that, for example, two capacitors Cn1 and Cn2 are connected to the gate of a NMOS transistor Qn11 as a source follower, and conduction/nonconduction control of switches Sn1 to Sn5 are performed, if needed, and by sequentially canceling the detected offsets, a final offset voltage is sufficiently reduced and high precision offset cancellation is realized.