According to the present invention, there is provided a control apparatus for an automotive alternator which includes a switch, a target voltage setter, a voltage regulator, and a disconnection detector. The switch is configured to be selectively turned on and off so as to intermittently excite the alternator. The target voltage setter works to set a target voltage. The voltage regulator works to regulate an output voltage of the alternator to the target voltage through controlling on/off operation the switch. The disconnection detector works to detect disconnection between the alternator and an on-board battery to be charged by the alternator. The disconnection detector is configured to detect the disconnection, when the target voltage is changed from a lower value to a higher value, based on a time required for the voltage regulator to bring the output voltage of the alternator from the lower value to the higher value.