Provided is a
hybrid driving device capable of transmitting a target torque to a speed change gear without deficiency and without excess, regarding a technology of starting up an engine by a driving force of a rotating electrical
machine during EV driving. The
hybrid driving device is provided with a rotating electrical
machine which is connected to a speed change gear through a hydraulic
power transmission having a lockup
clutch; and an engine start control device which starts an engine by controlling the number of rotations so that the number of rotations of the rotating electrical
machine becomes a target number of rotations, by slipping the lockup
clutch, prior to starting the engine. A transmission torque
estimation means for estimating a transmission torque which is transmitted by the lockup
clutch, under the condition that the lockup clutch slips, and a target rotation number determination means for determining a target number of rotations regarding the rotation number control for the rotating electrical machine, on the basis of the transmission torque estimated by the transmission torque
estimation means, a target input torque to the speed change gear, and an actual
turbine rotation number, are provided. The engine start control device controls the velocity so that the rotating electrical machine has the determined target number of rotations.