An apparatus comprises a changeover mechanism which is able to change a connection state of an electric motor output shaft to any one of states including, “an IN-Connection State” in which a power transmission path is provided between a transmission input shaft and the electric motor output shaft, “an OUT-Connection State” in which a power transmission path is provided between the transmission output shaft and the electric motor output shaft, and “a neutral connection state” in which no transmission path therebetween is provided. The changeover is carried out based on a combination (area) of a vehicle speed V and a required driving torque T. As for the changeover, an IN-connection area, in which an electric-motor-driving-wheels-maximum-torque is larger than in an OUT-Connection State and in a neutral connection area, is enlarged.