In a power train in which a differential mechanism is coupled with a transmission mechanism, a transmission member is free with no engagement in a second shift portion when a P position or an N position is selected, and a ring gear thereby becomes free in a power split device. During an idle operation with such a shift position, a behavior of an engine rotation speed is retained in a stable manner in the power split device which functions as the differential mechanism through a power supply control (lock control) such that a rotor of a second MG coupled with the ring gear is locked by an electromagnetic force, and then, a learning control of an idle speed control is appropriately implemented.