In an longitudinal type automatic transmission having an input shaft having driving gears, an output shaft having driven gears that are engaged with the driving gears to constitute transmission gear trains, and changeover mechanisms for selecting into a transmission gear train for transmitting a power, the automatic transmission is constructed to have the input shaft, the output shaft, and a driving shaft coupled to a final reduction gear, and has a bypass clutch that is arranged over the final reduction gear to transmit a torque to the output shaft while executing the control in a shifting operation and a start clutch for coupling or decoupling an engine and the input shaft. An oil pump for driving the start clutch and the bypass clutch is arranged over the final reduction gear and near the bypass clutch.