Abstract: In a drive force reduction controller for reducing engine output when drive wheels slip, a first shift timing is applied to an automatic transmission during ordinary running, and a second shift timing is applied when engine output is reduced. The second shift timing is set so as to provide a shift-up at a vehicle speed higher than the first shift timing when the throttle opening is less than a predetermined opening such that the engine rotation speed after shift-up is equal to or greater than a predetermined rotation speed. It is also set to provide the shift-up at a vehicle speed lower than the first shift timing when the throttle opening is greater than a second predetermined opening greater than the first predetermined opening. In this way, stable drive force reduction control is performed regardless of the throttle opening, shift-up in the high vehicle speed region is prevented, and shocks due to shift-up of the transmission in the high vehicle speed region are mitigated.