A planetary gear train of an automatic transmission may include an input shaft; an output gear; 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 combing third and fourth planetary gear sets; eight rotational members 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 seven friction members including three clutches interposed between a selected rotational member among the rotational members and the input shaft and adapted to selectively transmit the torque and four brakes interposed between a rotational member among the rotational members and a transmission housing.