There is provided an automatic transmission comprising a first shaft capable of receiving torque from an engine, and four planetary gear sets arranged coaxially on the first shaft and in series in an axial direction of the first shaft. Each of the four planetary gear sets has a single sun gear and a single ring gear. Further, the automatic transmission comprises an output wheel arranged coaxially on the first shaft, and capable of outputting torque transmitted from the engine through some of the four planetary gear sets. The output wheel is arranged between two of the four planetary gear sets. Accordingly, the noise or vibration from the planetary gear sets in the automatic transmission may be reduced, while the overall length of the first shaft may be made shorter, and the overall size of the automatic transmission may be made smaller.