A planetary gear train may include an input shaft, an output gear adapted to output a shifted torque, a first compound planetary gear set having four rotation elements by combining first and second planetary gear sets, a second compound planetary gear set having four rotation elements by combining third and fourth planetary gear sets, eight rotation shafts including two rotation elements connected to each other or one rotation element among the rotation elements of the first and second compound planetary gear sets, and six friction members including three clutches interposed between a selected rotational shaft among the rotational shafts and the input shaft and adapted to selectively transmit the torque and three brakes interposed between a selected rotational shaft among the rotational shafts and a transmission housing.