A control system for an automatic transmission, which is capable of controlling the hydraulic pressures for frictional engagement units when a predetermined shift is performed such that a first frictional engagement unit is engaged and a second frictional engagement unit is released, being connected to a power source, the revolving speed of which is temporarily raised when a predetermined shift down is performed, the control unit for the automatic transmission for a vehicle being structured such that shift which is performed by engaging and releasing the two frictional engagement units is judged, whether the judged shift is shift down in which the revolving speed of the power source is temporarily raised or shift down in which the revolving speed of the power source is not raised is judged, and the contents of control of the hydraulic pressures for the frictional engagement units are changed between shift down in which the revolving speed of the power source is temporarily raised and shift down in which the revolving speed of the power source is not raised.