To provide a mode transition control device of a hybrid car capable of providing smooth and excellent reacceleration performance, in traveling for reaccelerating after decelerating a vehicle by selecting a continuously variable shift mode.

This hybrid car has a differential device for arranging four or more of input-output elements on an alignment chart, and has a driving force synthesizing transmission TM for respectively allocating input from an engine E to one of two elements arranged inside among the input-output elements and an output shaft OUT to a driving system to the other, and respectively connecting a first motor generator MG1 and a second motor generator MG2 to the two elements arranged on both outsides of the inside element. The hybrid car has " the continuously variable shift mode " of traveling by at least the continuously variable gear ratio and " a low gear fixing mode " of traveling by the low side fixed gear ratio by fixing a rotational element of the differential device to a transmission case, as a traveling mode. The hybrid car is provided with a reacceleration corresponding mode transition control means for forcibly transferring the mode to " the low gear fixing mode " from " the continuously variable shift mode ", when a vehicle speed becomes a preset vehicle speed or less, when decelerating the vehicle by selecting " the continuously variable shift mode ".

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