The purpose of the invention is to provide an automatic transmission devised to reduce manipulation discomfort between a forward first-speed and a reverse-speed while also minimizing any increase in scale of planetary gear sets. When the three rotational elements of each of the first to fourth planetary gear sets 2-5 are arranged on a common velocity diagram in dependence upon distances corresponding to teeth-number ratios of the first to fourth planetary gear sets 2-5, the respective rotational elements are defined as first to twelfth elements in order of arrangement on the common velocity diagram. The first planetary gear set 2 is configured to integrally rotate by a first clutch 8. The first element 22 is coupled with the fifth element 34. The second element 24 is configured to be locked through a first brake 6 to a stationary section 13 and configured to be coupled through a second clutch 9 with the ninth element 41. The third element 21 is coupled with the input shaft 1. The fourth element 32 is configured to be coupled through a third clutch 10 with the ninth element 41. The sixth element 31 is locked to the stationary section 13. The seventh element 42 is configured to be locked through a second brake 7 to the stationary section 13. The eighth element 44 is coupled with an output shaft 12. The ninth element 41 is coupled with the twelfth element 51. The tenth element 52 is configured to be coupled through a fourth clutch 11 with the output shaft 12. The eleventh element 54 is coupled with the input shaft 1.
