An automatic transmission, which establishes automatic shifts in a multiple gear stages by selectively inputting a plurality of input rotations to a planetary gear set, includes first and third clutches connected through a reduction planetary gear to an input shaft and transmits a decelerated rotation to the planetary gear set and a second clutch directly connected to the input shaft and transmits a non-decelerated rotation to the planetary gear set. The reduction planetary gear is arranged on the end of a boss portion of a transmission case wall and the one element is fixed to the end of the boss portion, hydraulic servos of the first and third clutches are arranged on the boss portion, a hydraulic servo of a second clutch is arranged in the other side of the reduction planetary gear from the hydraulic servos, and the hydraulic paths for the hydraulic servos are formed in the boss portion.