A control apparatus of an automatic transmission including a start intended operation detecting unit detecting a vehicle starting operation; and a clutch control unit engaging the clutch from the clutch disengaged state and the automatic speed change mechanism is placed in a neutral state, when the vehicle starting operation is detected. The clutch control unit includes an initial engagement control unit performing initial engagement control that starts frictional contact of the clutch by supplying hydraulic pressure to a hydraulic servo of the clutch, and a slip start control unit establishing a speed ratio of the automatic speed change mechanism at the start by slip-controlling the clutch after the initial engagement control is terminated, thereby increasing output shaft rotational speed of the automatic speed change mechanism without reducing the input shaft rotational speed of the automatic speed change mechanism to less than the input shaft rotational speed at the end of initial engagement control.