A shift shock reduction system comprises a first section that causes an engine to produce a normal engine torque in accordance with an existing operation condition of a vehicle; a second section that changes an output rotation of the engine to an output rotation of an automatic transmission in accordance with an existing gear ratio derived from a rate between a rotation speed of an input member of the transmission and that of an output member of the same; a third section that corrects the engine torque upon sensing start of a shift shock reduction operation; a fourth section that detects completion of the correction of the engine torque; and a fifth section that returns the corrected engine torque to the normal engine torque upon sensing the completion of the engine torque correction. The fourth section detects the completion of the engine torque correction by making reference to a change rate per time of the existing gear ratio.