The primary purpose of the present invention is to provide a multi-stage transmission that can improve both motive power transmission efficiency and drivability without an increase in the size of the transmission. This automatic transmission (20) comprises the following: a Simpson compound planetary gear train (25) that comprises single-pinion-type first and second planetary gears (21, 22) and single-pinion-type third and fourth planetary gears (23, 24); first through fourth clutches (C1-C4); and first and second brakes (B1, B2). A first carrier (21c) of the first planetary gear (21) is linked to an input shaft (20i). A first ring gear (21r) of the first planetary gear (21) is selectively connected to an output shaft (20o) by the first clutch (C1).