An automatic transmission is provided having appropriately spaced gear ratios for eight forward speeds to be capable of obtaining a shift feeling in all of the eight speeds, and is reduced in size and weight. Rotation of an input shaft is transmitted to an output shaft at a speed selected from a plurality of shift speeds by first and second clutches selectively transmitting the rotation of the input shaft to first and second compound planetary gears, and by first to fourth brakes selectively fixing each element of the first and second compound planetary gears, the first compound planetary gear includes first and second sun gears, a common carrier rotatably supporting a long pinion and a pinion, and a common ring gear that meshes with the first sun gear through the long pinion or the pinion and also meshes with the second sun gear through the long pinion and the pinion.