A vehicle driving system (1, 1A) comprising an internal combustion engine and an electric motor, the system (1, 1A) comprising: an internal combustion engine output shaft by which power is outputted from the internal combustion engine; a first input shaft which is disposed parallel to the internal combustion engine output shaft and which is selectively connected to the internal combustion engine output shaft by a first engaging and disengaging unit; a second input shaft which is disposed parallel to the internal combustion engine output shaft and which is selectively connected to the internal combustion engine output shaft by a second engaging and disengaging unit; an output/input shaft which is disposed parallel to the internal combustion engine output shaft and which outputs power to a driven portion; a first gear group which is disposed on the first input shaft and which includes a plurality of gears (22a, 25a, 97a) which are selectively connected to the first input shaft via a first changeover unit (51, 51A, 52B, 61); a second gear group which is disposed on the second input shaft and which includes a plurality of gears (21a, 24a, 96a) which are selectively connected to the second input shaft via a second changeover unit (52, 52A, 52B); and a third gear group which is disposed on the output/input shaft and which includes a plurality of gears (23b, 24b, 96) with which the gears of the first gear group and the gears of the second gear group mesh, characterized in that when the vehicle is decelerated during an EV running by selecting a high-speed side gear of the first gear group, a braking force during a downshift is ensured by actuating wheel brakes (B1, B2, B3, B4) in a cooperative fashion so as to compensate for a reduction in regenerative braking force of the electric motor during a downward gear change from the high-speed side gear of the first gear group to a low-speed side gear of the first gear group while regeneration is brought about by the electric motor. an internal combustion engine output shaft by which power is outputted from the internal combustion engine; a first input shaft which is disposed parallel to the internal combustion engine output shaft and which is selectively connected to the internal combustion engine output shaft by a first engaging and disengaging unit; a second input shaft which is disposed parallel to the internal combustion engine output shaft and which is selectively connected to the internal combustion engine output shaft by a second engaging and disengaging unit; an output/input shaft which is disposed parallel to the internal combustion engine output shaft and which outputs power to a driven portion; a first gear group which is disposed on the first input shaft and which includes a plurality of gears (22a, 25a, 97a) which are selectively connected to the first input shaft via a first changeover unit (51, 51A, 52B, 61); a second gear group which is disposed on the second input shaft and which includes a plurality of gears (21a, 24a, 96a) which are selectively connected to the second input shaft via a second changeover unit (52, 52A, 52B); and a third gear group which is disposed on the output/input shaft and which includes a plurality of gears (23b, 24b, 96) with which the gears of the first gear group and the gears of the second gear group mesh, characterized in that when the vehicle is decelerated during an EV running by selecting a high-speed side gear of the first gear group, a braking force during a downshift is ensured by actuating wheel brakes (B1, B2, B3, B4) in a cooperative fashion so as to compensate for a reduction in regenerative braking force of the electric motor during a downward gear change from the high-speed side gear of the first gear group to a low-speed side gear of the first gear group while regeneration is brought about by the electric motor.